description: Theofanis started playing the new online game called "Among them". However, he always plays with Cypriot players, and they all have the same name: "Andreas" (the most common name in Cyprus).
  
  In each game, Theofanis plays with n other players. Since they all have the same name, they are numbered from 1 to n.
  
  The players write m comments in the chat. A comment has the structure of "i j c" where i and j are two distinct integers and c is a string (1 ≤ i, j ≤ n; i ≠ j; c is either imposter or crewmate). The comment means that player i said that player j has the role c.
  
  An imposter always lies, and a crewmate always tells the truth. 
  
  Help Theofanis find the maximum possible number of imposters among all the other Cypriot players, or determine that the comments contradict each other (see the notes for further explanation).
  
  Note that each player has exactly one role: either imposter or crewmate.
  
  Input
  
  The first line contains a single integer t (1 ≤ t ≤ 10^4) — the number of test cases. Description of each test case follows.
  
  The first line of each test case contains two integers n and m (1 ≤ n ≤ 2 ⋅ 10^5; 0 ≤ m ≤ 5 ⋅ 10^5) — the number of players except Theofanis and the number of comments.
  
  Each of the next m lines contains a comment made by the players of the structure "i j c" where i and j are two distinct integers and c is a string (1 ≤ i, j ≤ n; i ≠ j; c is either imposter or crewmate).
  
  There can be multiple comments for the same pair of (i, j).
  
  It is guaranteed that the sum of all n does not exceed 2 ⋅ 10^5 and the sum of all m does not exceed 5 ⋅ 10^5.
  
  Output
  
  For each test case, print one integer — the maximum possible number of imposters. If the comments contradict each other, print -1.
  
  Example
  
  Input
  
  
  5
  3 2
  1 2 imposter
  2 3 crewmate
  5 4
  1 3 crewmate
  2 5 crewmate
  2 4 imposter
  3 4 imposter
  2 2
  1 2 imposter
  2 1 crewmate
  3 5
  1 2 imposter
  1 2 imposter
  3 2 crewmate
  3 2 crewmate
  1 3 imposter
  5 0
  
  
  Output
  
  
  2
  4
  -1
  2
  5
  
  Note
  
  In the first test case, imposters can be Andreas 2 and 3.
  
  In the second test case, imposters can be Andreas 1, 2, 3 and 5.
  
  In the third test case, comments contradict each other. This is because player 1 says that player 2 is an imposter, and player 2 says that player 1 is a crewmate. If player 1 is a crewmate, then he must be telling the truth, so player 2 must be an imposter. But if player 2 is an imposter then he must be lying, so player 1 can't be a crewmate. Contradiction.
solution: import java.io.BufferedReader;
  import java.io.FileInputStream;
  import java.io.FileNotFoundException;
  import java.io.IOException;
  import java.io.InputStreamReader;
  import java.util.*;
  import java.util.concurrent.LinkedBlockingDeque;
  
  import javax.print.attribute.HashAttributeSet;
  import javax.swing.JLabel;
  
  import java.io.PrintStream;
              
                  public class Solution {
  
                      public static boolean Local(){
                          try{ 
                              return System.getenv("LOCAL_SYS")!=null;
                          }catch(Exception e){
                              return false;
                          }
                      }   
  
                      public static boolean LOCAL;
  
                      static class FastScanner {
  
                              BufferedReader br;
                              StringTokenizer st ;
  
                              FastScanner(){
                                  br =  new BufferedReader(new InputStreamReader(System.in));
                                  st = new StringTokenizer("");
                              }
  
                              FastScanner(String file) {
  
                                  try{
                                      br =  new BufferedReader(new InputStreamReader(new FileInputStream(file)));
                                      st = new StringTokenizer("");
                                  }catch(FileNotFoundException e) {
                                      // TODO Auto-generated catch block
                                      System.out.println("file not found");
                                      e.printStackTrace();
                                  }
                                  
                              }
                              
  
                              String next() {
                                  while (!st.hasMoreTokens())
                                      try {
                                          st = new StringTokenizer(br.readLine());
                                      } catch (IOException e) {
                                      }
                                  return st.nextToken();
                              }
  
                              int nextInt() {
                                  return Integer.parseInt(next());
                              }
  
                              long nextLong() {
                                  return Long.parseLong(next());
                              }
                              String readLine() throws IOException{
                                  return br.readLine();
                              }
                          }
                                              
                      static class Pair<T,X> {
  
                          T first;
                          X second;
                          
                          Pair(T first,X second){
                              this.first = first;
                              this.second = second;
                          }
  
                          @Override
                          public int hashCode(){
                              return Objects.hash(first,second);
                          }
  
                          @Override
                          public boolean equals(Object obj){
                              return obj.hashCode() == this.hashCode();
                          }
  
                      }
  
                  
                  static PrintStream debug = null;
  
                  static long mod = (long)(Math.pow(10,9) + 7); 
                  
  
                  public static void main(String[] args) throws Exception {
                      
                      FastScanner s = new FastScanner();
  
                      LOCAL = Local();
  
                      
                      if(LOCAL){
                          s = new FastScanner("src/input.txt");
                          PrintStream o = new PrintStream("src/sampleout.txt");
                          debug = new PrintStream("src/debug.txt");
                          System.setOut(o);
                      }
  
                      long mod = 1000000007;
                      
                      int tcr =  s.nextInt();     
                  
                      StringBuilder sb = new StringBuilder();
  
                      
                  
                      for(int tc=0;tc<tcr;tc++){
                          List<List<int[]>> graph = new ArrayList<>();
                          int n = s.nextInt();
                          int m = s.nextInt();
                          for(int i=0;i<n;i++){graph.add(new ArrayList<>());}
                          int val[] = new int[n];
                          Arrays.fill(val,-1);
                          boolean poss = true;
                          
  
                          for(int i=0;i<m;i++){
                              int v1 = s.nextInt();
                              int v2 = s.nextInt();
                              v1--;
                              v2--;
                              String str = s.next();
                              int valc = str.equals("imposter")?0:1;
                              graph.get(v1).add(new int[]{v2,valc});
                              graph.get(v2).add(new int[]{v1,valc});
                          }
  
                          int ans = 0;
  
                          boolean visited[] = new boolean[n];
  
                          for(int i=0;i<n;i++){
                              if(!visited[i]){
                                  int fans[] = dfs(i,graph,visited,val,1);
                                  if(fans[0] == -1){
                                      poss  = false;break;
                                  }
                                  int z = fans[0];
                                  int o = fans[1];
                                  ans += Math.max(z,o);
                              }
                          }
                          if(!poss){sb.append(-1+"\n");continue;}
                          sb.append(ans+"\n");
                      }
  
  
                      print(sb.toString());
                  }
  
                  public static int[] dfs(int v,List<List<int[]>> graph,boolean vis[],int val[],int my_val){
                      
                      vis[v] = true;
                      
                      val[v] = my_val;
  
                      int cnt_0 = 0;
                      
                      int cnt_1 = 0;
  
                      for(int[] edge : graph.get(v)){
                          int edge_val = edge[1];
                          if(!vis[edge[0]]){
                              int ans[] = dfs(edge[0],graph,vis,val,(my_val == 0 ? (1 ^ edge_val):(edge_val)));
                              if(ans[0] == -1){
                                  return ans;
                              }
                              cnt_0 += ans[0];
                              cnt_1 += ans[1];
                          }else{
                              if(my_val == 0){edge_val = (1 ^ edge_val);}
                              if(val[edge[0]] != edge_val){
                                  return new int[]{-1,-1};
                              }
                          }
                      }
                      if(my_val == 0){cnt_0++;}
                      else{cnt_1++;}
                      return new int[]{cnt_0,cnt_1};
                  }
  
                  public static long ncr(int n,int r,long fact[]){
                      if(r==0){return 1l;}
                      long ans = fact[n];
                      long denom = mulmod(fact[r], fact[n-r], mod);
                      ans = mulmod(ans,modpow(denom,mod-2, mod),mod);
                      return ans;
                  }
  
                  public static List<long[]> prime_factors(long n){
              
                      List<long[]> list = new ArrayList<>();
                      
                      for(long i=2;i<=(Math.sqrt(n));i++){
              
                          if(n % i == 0){
                              
                              int cnt = 0;
                              
                              while( (n % i) == 0){
                                  n = n/i;
                                  cnt++;
                                  
                              }
              
                              list.add(new long[]{i,cnt});
                          }
                      }
  
              
                      if(n!=1){
                          list.add(new long[]{n,1l});
                      }
              
                      return list;
              
                  }
  
                  public static boolean check(int arr[]){
                      for(int i=1;i<arr.length;i++){
                          if(arr[i] < arr[i-1]){
                              return false;
                          }
                      }
                      return true;
                  }
  
              
                  public static boolean inRange(int r1,int r2,int val){
                      return ((val >= r1) && (val <= r2));
                  }
  
                  static int len(long num){
                      return Long.toString(num).length();
                  }
  
                  static long mulmod(long a, long b,long mod)
                  {
                      long ans = 0l;
                      
                      while(b > 0l){
                          long curr = (b & 1l);
                          if(curr == 1l){
                              ans = ((ans % mod) + a) % mod;
                          }
                          
                          a = (a + a) % mod;
  
                          b = b >> 1;
                      }
  
                      return ans;
                  }
  
  
                  public static void dbg(PrintStream ps,Object... o) throws Exception{
                      if(ps == null){
                          return;
                      }
                      Debug.dbg(ps,o);
                  }
  
                  public static long modpow(long num,long pow,long mod){
  
                      long val = num;
                      long ans = 1l;
  
                      while(pow > 0l){
                          
                          long bit = pow & 1l;
  
                          if(bit == 1){
                              ans = (ans * (val%mod))%mod;
                          }
  
                          val = (val * val) % mod;
                          pow = pow >> 1;
                      }
  
                      return ans;
  
                  }
  
                  public static char get(int n){
                      return (char)('a' + n);
                  }
  
                  public static long[] sort(long arr[]){
                      List<Long> list = new ArrayList<>();
                      for(long n : arr){list.add(n);}
                      Collections.sort(list);
                      for(int i=0;i<arr.length;i++){
                          arr[i] = list.get(i);
                      }
                      return arr;
                  }
  
                  public static int[] sort(int arr[]){
                      List<Integer> list = new ArrayList<>();
                      for(int n : arr){list.add(n);}
                      Collections.sort(list);
                      for(int i=0;i<arr.length;i++){
                          arr[i] = list.get(i);
                      }
                      return arr;
                  }
  
                  // return the (index + 1)
                  // where index is the pos of just smaller element
                  // i.e count of elemets strictly less than num
                  public static int justSmaller(long arr[],long num){
                      //  System.out.println(num+"@");
                      int st = 0;
                      int e = arr.length - 1;
              
                      int ans = -1;
              
                      while(st <= e){
              
                          int mid = (st + e)/2;
              
                          if(arr[mid] >= num){
                              e = mid - 1;
                          }else{
                              ans = mid;
                              st = mid + 1;
                          }
              
                      }
              
              
                      return ans + 1;
              
                  }
                  public static int justSmaller(int arr[],int num){
                      //  System.out.println(num+"@");
                      int st = 0;
                      int e = arr.length - 1;
              
                      int ans = -1;
              
                      while(st <= e){
              
                          int mid = (st + e)/2;
              
                          if(arr[mid] >= num){
                              e = mid - 1;
                          }else{
                              ans = mid;
                              st = mid + 1;
                          }
              
                      }
              
              
                      return ans + 1;
              
                  }
                  
                  //return (index of just greater element)
                  //count of elements smaller than or equal to num
  
                  public static int justGreater(long arr[],long num){
                      int st = 0;
                      int e = arr.length - 1;
              
                      int ans = arr.length;
              
                      while(st <= e){
                          
                          int mid = (st + e)/2;
              
                          if(arr[mid] <= num){
                              st = mid + 1;
                          }else{
                              ans = mid;
                              e = mid - 1;
                          }
                      }
              
                      return ans;
              
                  }
  
                  public static int justGreater(int arr[],int num){
                      int st = 0;
                      int e = arr.length - 1;
              
                      int ans = arr.length;
              
                      while(st <= e){
                          
                          int mid = (st + e)/2;
              
                          if(arr[mid] <= num){
                              st = mid + 1;
                          }else{
                              ans = mid;
                              e = mid - 1;
                          }
                      }
              
                      return ans;
              
                  }
              
                  
  
                  public static void println(Object obj){
                      System.out.println(obj.toString());
                  }
  
                  public static void print(Object obj){
                      System.out.print(obj.toString());
                  }
  
                  public static int gcd(int a,int b){
                      if(b == 0){return a;}
                      return gcd(b,a%b);
                  }
  
                  public static long gcd(long a,long b){
                      if(b == 0l){
                          return a;
                      }
  
                      return gcd(b,a%b);
                  }
  
                  public static int find(int parent[],int v){
                      if(parent[v] == v){
                          return v;
                      }
                      
                      return parent[v] = find(parent, parent[v]);
                  }
  
              
  
                  public static List<Integer> sieve(){
                  
                          List<Integer> prime = new ArrayList<>();
  
                          int arr[] = new int[300001];
  
                      Arrays.fill(arr,1);
  
                      arr[1] = 0;
                      arr[2] = 1;
  
                      for(int i=2;i<300001;i++){
                          
                          if(arr[i] == 1){
                              
                              prime.add(i);
  
                              for(long j = (i*1l*i);j<300001;j+=i){
                                  arr[(int)j] = 0;
                              }
                          }
                      }
  
                      return prime;
                  }
  
                  static boolean isPower(long n,long a){
                      
                      long log = (long)(Math.log(n)/Math.log(a));
  
                      long power = (long)Math.pow(a,log);
  
                      if(power == n){return true;}
  
                      return false;
                  }
  
  
                  private static int mergeAndCount(int[] arr, int l,int m, int r)
                  {
  
                      // Left subarray
                      int[] left =  Arrays.copyOfRange(arr, l, m + 1);
  
                      // Right subarray
                      int[] right = Arrays.copyOfRange(arr, m + 1, r + 1);
  
                      int i = 0, j = 0, k = l, swaps = 0;
  
                      while (i < left.length && j < right.length) {
                          if (left[i] <= right[j])
                              arr[k++] = left[i++];
                          else {
                              arr[k++] = right[j++];
                              swaps += (m + 1) - (l + i);
                          }
                      }
                      while (i < left.length)
                          arr[k++] = left[i++];
                      while (j < right.length)
                          arr[k++] = right[j++];
                      return swaps;
                  }
  
                  // Merge sort function
                  private static int mergeSortAndCount(int[] arr, int l,int r)
                  {
  
                      // Keeps track of the inversion count at a
                      // particular node of the recursion tree
                      int count = 0;
  
                      if (l < r) {
                          int m = (l + r) / 2;
  
                          // Total inversion count = left subarray count
                          // + right subarray count + merge count
  
                          // Left subarray count
                          count += mergeSortAndCount(arr, l, m);
  
                          // Right subarray count
                          count += mergeSortAndCount(arr, m + 1, r);
  
                          // Merge count
                          count += mergeAndCount(arr, l, m, r);
                      }
  
                      return count;
                  }
  
                  static class Debug{
                      //change to System.getProperty("ONLINE_JUDGE")==null; for CodeForces
                      public static final boolean LOCAL = System.getProperty("ONLINE_JUDGE")==null;
  
                      
  
                      private static <T> String ts(T t) {
                          if(t==null) {
                              return "null";
                          }
                          try {
                              return ts((Iterable) t);
                          }catch(ClassCastException e) {
                              if(t instanceof int[]) {
                                  String s = Arrays.toString((int[]) t);
                                  return "{"+s.substring(1, s.length()-1)+"}\n";
                              }else if(t instanceof long[]) {
                                  String s = Arrays.toString((long[]) t);
                                  return "{"+s.substring(1, s.length()-1)+"}\n";
                              }else if(t instanceof char[]) {
                                  String s = Arrays.toString((char[]) t);
                                  return "{"+s.substring(1, s.length()-1)+"}\n";
                              }else if(t instanceof double[]) {
                                  String s = Arrays.toString((double[]) t);
                                  return "{"+s.substring(1, s.length()-1)+"}\n";
                              }else if(t instanceof boolean[]) {
                                  String s = Arrays.toString((boolean[]) t);
                                  return "{"+s.substring(1, s.length()-1)+"}\n";
                              }
                              try {
                                  return ts((Object[]) t);
                              }catch(ClassCastException e1) {
                                  return t.toString();
                              }
                          }
                      }
                      private static <T> String ts(T[] arr) {
                          StringBuilder ret = new StringBuilder();
                          ret.append("{");
                          boolean first = true;
                          for(T t: arr) {
                              if(!first) {
                                  ret.append(", ");
                              }
                              first = false;
                              ret.append(ts(t));
                          }
                          ret.append("}");
                          return ret.toString();
                      }
                      private static <T> String ts(Iterable<T> iter) {
                          StringBuilder ret = new StringBuilder();
                          ret.append("{");
                          boolean first = true;
                          for(T t: iter) {
                              if(!first) {
                                  ret.append(", ");
                              }
                              first = false;
                              ret.append(ts(t));
                          }
                          ret.append("}");
                          return ret.toString();
                      }
                      public static void dbg(PrintStream ps,Object... o) throws Exception {
                          if(LOCAL) {
                              System.setErr(ps);
                              System.err.print("Line #"+Thread.currentThread().getStackTrace()[2].getLineNumber()+": [");
                              for(int i = 0; i<o.length; i++) {
                                  if(i!=0) {
                                      System.err.print(", ");
                                  }
                                  System.err.print(ts(o[i]));
                              }
                              System.err.println("]");
                          }
                      }
                  }
  
          }
  
  
          