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.OutputStream;
  import java.io.IOException;
  import java.io.InputStream;
  import java.io.PrintWriter;
  import java.io.BufferedReader;
  import java.io.InputStreamReader;
  import java.util.*;
  
  public class Main {
      public static void main(String[] args){
          InputStream inputStream = System.in;
          OutputStream outputStream = System.out;
          InputReader in = new InputReader(inputStream);
          PrintWriter out = new PrintWriter(outputStream);
          solve(in, out);
          out.close();
      }
  
      static String reverse(String s) {
          return (new StringBuilder(s)).reverse().toString();
      }
  
      static void sieveOfEratosthenes(int n, int factors[], ArrayList<Integer> ar) 
      { 
          factors[1]=1;
          int p;
          for(p = 2; p*p <=n; p++) 
          { 
              if(factors[p] == 0) 
              { 
                  ar.add(p);
                  factors[p]=p;
                  for(int i = p*p; i <= n; i += p) 
                      if(factors[i]==0)
                          factors[i] = p; 
              } 
          } 
          for(;p<=n;p++){
              if(factors[p] == 0) 
              { 
                  factors[p] = p;
                  ar.add(p);
              } 
          }
      }
  
      static void sort(int ar[]) {
          int n = ar.length;
          ArrayList<Integer> a = new ArrayList<>();
          for (int i = 0; i < n; i++)
              a.add(ar[i]);
          Collections.sort(a);
          for (int i = 0; i < n; i++)
              ar[i] = a.get(i);
      }
  
      static void sort1(long ar[]) {
          int n = ar.length;
          ArrayList<Long> a = new ArrayList<>();
          for (int i = 0; i < n; i++)
              a.add(ar[i]);
          Collections.sort(a);
          for (int i = 0; i < n; i++)
              ar[i] = a.get(i);
      }
  
      static void sort2(char ar[]) {
          int n = ar.length;
          ArrayList<Character> a = new ArrayList<>();
          for (int i = 0; i < n; i++)
              a.add(ar[i]);
          Collections.sort(a);
          for (int i = 0; i < n; i++)
              ar[i] = a.get(i);
      }
  
      static long ncr(long n, long r, long mod) {
          if (r == 0)
              return 1;
          long val = ncr(n - 1, r - 1, mod);
          val = (n * val) % mod;
          val = (val * modInverse(r, mod)) % mod;
          return val;
      }
  
      static long sum[];
      static long lz[];
      
      static void build(long a[], int v, int tl, int tr) {
          if (tl == tr) {
              sum[v] = a[tl];
              
          } else {
              int tm = (tl + tr) / 2;
              build(a, v*2, tl, tm);
              build(a, v*2+1, tm+1, tr);
              sum[v] = sum[v*2] + sum[v*2+1];
          }
      }
  
      static void push(int v, int tl, int tr){
          if(tl==tr){
              lz[v] = 0;
              return;
          }
          sum[2*v] += lz[v];
          sum[2*v] %= m;
          sum[2*v+1] += lz[v];
          sum[2*v+1] %= m;
          lz[2*v] += lz[v];
          lz[2*v] %= m;
          lz[2*v+1] += lz[v];
          lz[2*v+1] %= m;
          lz[v] = 0;
      }
  
      static void update(int v, int tl, int tr, int l, int r, long val) {
          push(v,tl,tr);
          if(tl>r||tr<l)
              return;
          if(tl>=l&&tr<=r){
              sum[v] += val;
              sum[v] %= m;
              lz[v] += val;
              lz[v] %= m;
              return;
          }
          int tm = ((tl + tr) >> 1);
          update(v*2, tl, tm, l, r, val);
          update(v*2+1, tm+1, tr, l, r, val);
          sum[v] = sum[2*v]+sum[2*v+1];
          sum[v] %= m;
      }
  
      static long get(int v, int tl, int tr, int l, int r) {
          push(v,tl,tr);
          if (tl >= l && tr <= r) {
              return sum[v];
          }
          int tm = ((tl + tr) >> 1);
          if(l>tm){
              return get(2*v+1, tm+1, tr, l, r);
          }
          if(r<tm+1){
              return get(2*v, tl, tm, l, r);
          }
          return (get(2*v, tl, tm, l, r) + get(2*v+1, tm+1, tr, l, r)) % m;
      }
  
      // static int y = 0;
  
      static int parent[];
      static int rank[];
  
      static long m = 0;
  
      static int find_set(int v) {
          if (v == parent[v])
              return v;
          return find_set(parent[v]);
      }
      
      static void make_set(int v) {
          parent[v] = v;
          rank[v] = 0;
      }
      
      static void union_sets(int a, int b) {
          a = find_set(a);
          b = find_set(b);
          if (a != b) {
              if (rank[a] < rank[b]){
                  int tmp = a;
                  a = b;
                  b = tmp;
              }
              parent[b] = a;
              if (rank[a] == rank[b])
                  rank[a]++;
          }
      }
  
      static int parent1[];
      static int rank1[];
  
      static int find_set1(int v) {
          if (v == parent1[v])
              return v;
          return find_set1(parent1[v]);
      }
      
      static void make_set1(int v) {
          parent1[v] = v;
          rank1[v] = 0;
      }
      
      static void union_sets1(int a, int b) {
          a = find_set1(a);
          b = find_set1(b);
          if (a != b) {
              if (rank1[a] < rank1[b]){
                  int tmp = a;
                  a = b;
                  b = tmp;
              }
              parent1[b] = a;
              if (rank1[a] == rank1[b])
                  rank1[a]++;
          }
      }
  
      static int count = 0;
      static int count1 = 0;
  
      public static void solve(InputReader sc, PrintWriter pw){
          int i, j = 0;
          // int t = 1; 
          long mod = 1000000007;
          int t = sc.nextInt();
          u: while (t-- > 0) {
              int n = sc.nextInt();
              int m = sc.nextInt();
              ArrayList<Integer> un[] = new ArrayList[n];
              ArrayList<Integer> ar1[] = new ArrayList[n];
              ArrayList<Integer> ar2[] = new ArrayList[n];
              for(i=0;i<n;i++){
                  un[i] = new ArrayList<>();
                  ar1[i] = new ArrayList<>();
                  ar2[i] = new ArrayList<>();
              }
              for(i=0;i<m;i++){
                  int a = sc.nextInt()-1;
                  int b = sc.nextInt()-1;
                  String s = sc.next();
                  if(s.equals("imposter")){
                      ar2[a].add(b);
                      ar2[b].add(a);
                  }
                  else{
                      ar1[a].add(b);
                      ar1[b].add(a);
                  }
                  un[a].add(b);
                  un[b].add(a);
              }
              int vis[] = new int[n];
              int c = 0;
              for(i=0;i<n;i++){
                  if(vis[i]>0){
                      
                  }
                  else{
                      c++;
                      dfs(i,un,vis,c);
                  }
              }
              c++;
              possible = true;
              int x[] = new int[c];
              int res[] = new int[c];
              int res2[] = new int[c];
              int v[] = new int[n];
              for(i=0;i<n;i++){
                  x[vis[i]]++;
              }
              // vis = new int[c];
              for(i=0;i<n;i++){
                  if(res[vis[i]]>0){
                      continue;
                  }    
                  // res[vis[i]] = 1;
                  // int val = check(i, ar1, ar2, v, res);
                  // if(val==0)
                  //     val = 1;
                  // v[i] = 1;
                  fill(i,ar1,ar2,vis,res,res2,v,1);
              }
              if(!possible){
                  pw.println(-1);
              }
              else{
                  int h = 0;
                  for(i=1;i<c;i++){
                      h += Math.max(res[i],res2[i]);
                  }
                  pw.println(h);
              }
          }
      }
  
      static boolean possible;
  
      static void fill(int curr, ArrayList<Integer> ar1[], ArrayList<Integer> ar2[], int vis[], int res[], int res2[], int v[], int c){
          if(v[curr]>0){
              if(v[curr]!=c){
                  possible = false;
              }
              return;
          }
          v[curr] = c;
          if(c==1)
              res[vis[curr]]++;
          else
              res2[vis[curr]]++;
          for(int y:ar1[curr]){
              fill(y,ar1,ar2,vis,res,res2,v,c);
          }
          for(int y:ar2[curr]){
              fill(y,ar1,ar2,vis,res,res2,v,3-c);
          }
      }
  
      // static int check(int curr, ArrayList<Integer> ar1[], ArrayList<Integer> ar2[], int v[], int res[]){
      //     if(v[curr]>0)
      //         return v[curr];
      //     int val = 0;
      //     for(int y:ar1[curr]){
      //         int r = check(y, ar1, ar2, v, res);
      //         if(r>0){
      //             return r;
      //         }
      //     }
      //     for(int y:ar2[curr]){
      //         int r = check(y, ar1, ar2, v, res);
      //         if(r>0){
      //             return 3-r;
      //         }
      //     }
      //     return 0;
      // }
  
  
  
      static void dfs(int curr, ArrayList<Integer> ar[], int vis[], int c){
          if(vis[curr]>0)
              return;
          vis[curr] = c;
          for(int y:ar[curr]){
              dfs(y,ar,vis,c);
          }
      }
      
      static int c = 0;
  
      static void KMPSearch(char pat[], char txt[], int pres[]){
          int M = pat.length;
          int N = txt.length;
          int lps[] = new int[M];
          int j = 0; 
          computeLPSArray(pat, M, lps);
          int i = 0;
          while (i < N) {
              if (pat[j] == txt[i]) {
                  j++;
                  i++;
              }
              if (j == M) {
                  pres[i-1] = 1;
                  j = lps[j - 1];
              }
              else if (i < N && pat[j] != txt[i]) {
                  if (j != 0)
                      j = lps[j - 1];
                  else
                      i = i + 1;
              }
          }
      }
    
      static void computeLPSArray(char pat[], int M, int lps[])
      {
          int len = 0;
          int i = 1;
          lps[0] = 0; 
          while (i < M) {
              if (pat[i] == pat[len]) {
                  len++;
                  lps[i] = len;
                  i++;
              }
              else 
              {
                  if (len != 0) {
                      len = lps[len - 1];
                  }
                  else
                  {
                      lps[i] = len;
                      i++;
                  }
              }
          }
      }
  
      static long[][] matrixMult(long a[][], long b[][], long mod){
          int n = a.length;
          int m = a[0].length;
          int p = b[0].length;
          long c[][] = new long[n][p];
          for(int i=0;i<n;i++){
              for(int j=0;j<m;j++){
                  for(int k=0;k<p;k++){
                      c[i][k] += a[i][j]*b[j][k];
                      c[i][k] %= mod;
                  }
              }
          }
          return c;
      }
  
      static long[][] exp(long mat[][], long b, long mod){
          if(b==0){
              int n = mat.length;
              long res[][] = new long[n][n];
              for(int i=0;i<n;i++){
                  res[i][i] = 1;
              }
              return res;
          }
          long half[][] = exp(mat, b/2, mod);
          long res[][] = matrixMult(half, half, mod);
          if(b%2==1){
              res = matrixMult(res, mat, mod);
          }
          return res;
      }
  
      static void countPrimeFactors(int num, int a[], HashMap<Integer,Integer> pos){
          for(int i=2;i*i<num;i++){
              if(num%i==0){
                  int y = pos.get(i);
                  while(num%i==0){
                      a[y]++;
                      num/=i;
                  }
              }
          }
          if(num>1){
              int y = pos.get(num);
              a[y]++;
          }
      }
  
      static void assignAnc(ArrayList<Integer> ar[], int depth[], int sz[], int par[][] ,int curr, int parent, int d){
          depth[curr] = d;
          sz[curr] = 1;
          par[curr][0] = parent;
          for(int v:ar[curr]){
              if(parent==v)
                  continue;
              assignAnc(ar, depth, sz, par, v, curr, d+1);
              sz[curr] += sz[v];
          }
      }
  
      static int findLCA(int a, int b, int par[][], int depth[]){
          if(depth[a]>depth[b]){
              a = a^b;
              b = a^b;
              a = a^b;
          }
          int diff = depth[b] - depth[a];
          for(int i=19;i>=0;i--){
              if((diff&(1<<i))>0){
                  b = par[b][i];
              }
          }
          if(a==b)
              return a;
          for(int i=19;i>=0;i--){
              if(par[b][i]!=par[a][i]){
                  b = par[b][i];
                  a = par[a][i];
              }
          }
          return par[a][0];
      }
  
      static void formArrayForBinaryLifting(int n, int par[][]){
          for(int j=1;j<20;j++){
              for(int i=0;i<n;i++){
                  if(par[i][j-1]==-1)
                      continue;
                  par[i][j] = par[par[i][j-1]][j-1];
              }
          }
      }
  
      static long lcm(int a, int b){
          return a*b/gcd(a,b);
      }
  
      static class Pair1 {
          long a;
          long b;
          
          Pair1(long a, long b) {
              this.a = a;
              this.b = b;
          }
      }
  
      static class Pair implements Comparable<Pair> {
          int a;
          int b;
          // int c;
          
          Pair(int a, int b) {
              this.a = a;
              this.b = b;
              // this.c = c;
          }
   
          public int compareTo(Pair p) {
              if(a!=p.a)
                  return a-p.a;
              return b-p.b;
          }
      }
  
      static class Pair2 implements Comparable<Pair2> {
          int a;
          int b;
          int c;
          
          Pair2(int a, int b, int c) {
              this.a = a;
              this.b = b;
              this.c = c;
          }
   
          public int compareTo(Pair2 p) {
              return a-p.a;
          }
      }
  
      static boolean isPrime(int n) { 
          if (n <= 1) 
              return false; 
          if (n <= 3) 
              return true; 
          if (n % 2 == 0 ||  n % 3 == 0) 
              return false; 
          for (int i = 5; i * i <= n; i = i + 6) 
              if (n % i == 0 || n % (i + 2) == 0) 
                  return false; 
          return true; 
      } 
  
      static long gcd(long a, long b) {
          if (b == 0)
              return a;
          return gcd(b, a % b);
      }
  
      static long fast_pow(long base, long n, long M) {
          if (n == 0)
              return 1;
          if (n == 1)
              return base % M;
          long halfn = fast_pow(base, n / 2, M);
          if (n % 2 == 0)
              return (halfn * halfn) % M;
          else
              return (((halfn * halfn) % M) * base) % M;
      }
  
      static long modInverse(long n, long M) {
          return fast_pow(n, M - 2, M);
      }
  
      static class InputReader {
          public BufferedReader reader;
          public StringTokenizer tokenizer;
  
          public InputReader(InputStream stream) {
              reader = new BufferedReader(new InputStreamReader(stream), 9992768);
              tokenizer = null;
          }
  
          public String next() {
              while (tokenizer == null || !tokenizer.hasMoreTokens()) {
                  try {
                      tokenizer = new StringTokenizer(reader.readLine());
                  } catch (IOException e) {
                      throw new RuntimeException(e);
                  }
              }
              return tokenizer.nextToken();
          }
  
          public int nextInt() {
              return Integer.parseInt(next());
          }
  
          public long nextLong() {
              return Long.parseLong(next());
          }
      }
  }