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.util.*;
  
  import java.io.*;
  import java.math.*;
  
  
  /**
   * @author Naitik
   * 
   */
  public class Main
  
  { 
  	 static FastReader sc=new FastReader(); 
  	 static long dp[][];
  	 //static int v[][];
  	 static int mod=998244353;;
  //	 static int mod=1000000007;
  	 static long max;
  	 static int a=0,b=0;
  	 static long bit[];
  //	 static long seg[];
  	 //static long fact[];
  //	 static long A[];
  	// static TreeMap<Integer,Integer> map;
  	 //static StringBuffer sb=new StringBuffer("");
  	 static HashMap<Integer,Integer> map;
  	   static PrintWriter out=new PrintWriter(System.out);
  	  public static void main(String[] args)
  {
  		  
  		 //  StringBuffer sb=new StringBuffer("");
  		  int ttt=1;
  		      ttt =i();
  	        outer :while (ttt-- > 0) 
  			{
  	        	max=0;
  	        	int n=i()+1;
  	        	int m=i();
  	        	ArrayList<Pair> A[]=new ArrayList[n];
  	        	for(int i=0;i<n;i++) {
  	        		A[i]=new ArrayList<Pair>();
  	        	}
  	        	for(int i=0;i<m;i++) {
  	        		int a=i();
  	        		int b=i();
  	        		char ch=s().charAt(0);
  	        		int x=0;
  	        		if(ch=='i') {
  	        			x=1;
  	        		}
  	        		Pair p1=new Pair(a,x);
  	        		Pair p2=new Pair(b,x);
  	        		A[a].add(p2);
  	        		A[b].add(p1);
  	        	}
  	        	boolean v[]=new boolean[n];
  	        	int dis[]=new int[n];
  	        	int ans=0;
  	        	for(int i=1;i<n;i++) {
  	        		if(!v[i]) {
  	        			a=0;
  	        			b=0;
  	        			go(A, i, v, dis, 0);
  	        			ans+=max(a,b);
  	        		}
  	        	}
  	        	if(max==-1)
  	        		System.out.println("-1");
  	        	else
  	        		System.out.println(ans);
  	        
  	        	
  	        }
  	        //System.out.println(sb.toString());
  		     out.close();
  	     
  	     
  	    //CHECK FOR N=1                    //CHECK FOR M=0
          //CHECK FOR N=1                    //CHECK FOR M=0
         	//CHECK FOR N=1
         	
  		        
  		     
      } 
  	  private static void go(ArrayList<Pair>[] A, int i, boolean[] v, int[] dis,int d) {
  			v[i]=true;
  			dis[i]=d;
  			if(d==0)
  				a++;
  			else
  			b++;
  					for(Pair child : A[i]) {
  						if(!v[child.x]) {
  							go(A, child.x, v, dis, d^child.y);
  						}
  						else {
  							if((d^child.y)!=dis[child.x]) {
  								max=-1;
  								return;
  							}
  						}
  					}
  				}
  	  
  	  
  	  
  	
  	
  	
  static class Pair implements Comparable<Pair>
       {
      	 int x;
      	 int y;
      	 int z;
      	 Pair(int x,int y){
      		 this.x=x;
      		 this.y=y;
      		// this.z=z;
      		 
      	 }
  		@Override
  		public int compareTo(Pair o) {
  			if(this.x>o.x)
  				return +1;
  			else if(this.x<o.x)
  				return -1;
  			else {
  				if(this.y>o.y)
  					return 1;
  				else if(this.y<o.y)
  					return -1;
  				else
  					return 0;
  			}
  		}
  //		public int hashCode() 
  //		{ 
  //			final int temp = 14; 
  //			int ans = 1; 
  //			ans =x*31+y*13; 
  //			return ans; 
  //		} 
  //		@Override
  //		public boolean equals(Object o) 
  //		{ 
  //			if (this == o) { 
  //				return true; 
  //			} 
  //			if (o == null) { 
  //				return false; 
  //			} 
  //			if (this.getClass() != o.getClass()) { 
  //				return false; 
  //			} 
  //			Pair other = (Pair)o; 
  //			if (this.x != other.x || this.y!=other.y) { 
  //				return false; 
  //			} 
  //			return true; 
  //		} 	
  //		
  		/* FOR TREE MAP PAIR USE */
  		
  //		public int compareTo(Pair o) {
  // 			if (x > o.x) {
  // 				return 1;
  // 			}
  // 			if (x < o.x) {
  // 				return -1;
  // 			}
  // 			if (y > o.y) {
  // 				return 1;
  // 			}
  // 			if (y < o.y) {
  // 				return -1;
  // 			}
  // 			return 0;
  // 		}
  		
       }
  
  //static int find(int A[],int a) {
  //	  if(A[a]<0)
  //		  return a;
  //	  return A[a]=find(A, A[a]);
  //}
  static int find(int A[],int a) {
  	  if(A[a]==a)
  		  return a;
  	  return A[a]=find(A, A[a]);
  }
  //FENWICK TREE
  static void update(int i, int x){
  	for(; i < bit.length; i += (i&-i))
  		bit[i] += x;
  }
  
  static int sum(int i){
  	int ans = 0;
  	for(; i > 0; i -= (i&-i))
  		ans += bit[i];
  	return ans;
  }
  //END
  static void add(int v) {
  	if(!map.containsKey(v)) {
  		map.put(v, 1);
  	}
  	else {
  		map.put(v, map.get(v)+1);
  	}
  }
  static void remove(int v) {
  	if(map.containsKey(v)) {
  		map.put(v, map.get(v)-1);
  		if(map.get(v)==0)
  			map.remove(v);
  	}
  }
  public static int upper(int A[],int k,int si,int ei)
  {
  	int l=si;
  	int u=ei;
  	int ans=-1;
  	while(l<=u) {
  		int mid=(l+u)/2;
  		if(A[mid]<=k) {
  			ans=mid;
  			l=mid+1;
  		}
  		else {
  			u=mid-1;
  		}
  	}
  	return ans;
  }
  public static int lower(int A[],int k,int si,int ei)
  {
  	int l=si;
  	int u=ei;
  	int ans=-1;
  	while(l<=u) {
  		int mid=(l+u)/2;
  		if(A[mid]<=k) {
  			l=mid+1;
  		}
  		else {
  			ans=mid;
  			u=mid-1;
  		}
  	}
  	return ans;
  	
      
  }
  static int[] copy(int A[]) {
  	int B[]=new int[A.length];
  	for(int i=0;i<A.length;i++) {
  		B[i]=A[i];
  	}
  	return B;
  }
  static long[] copy(long A[]) {
  	long B[]=new long[A.length];
  	for(int i=0;i<A.length;i++) {
  		B[i]=A[i];
  	}
  	return B;
  }
  static int[] input(int n) {
  	int A[]=new int[n];
  	   for(int i=0;i<n;i++) {
  		   A[i]=sc.nextInt();
  	   }
  	   return A;
     }
  static long[] inputL(int n) {
  	long A[]=new long[n];
  	   for(int i=0;i<n;i++) {
  		   A[i]=sc.nextLong();
  	   }
  	   return A;
     }
  static String[] inputS(int n) {
  	String A[]=new String[n];
  	   for(int i=0;i<n;i++) {
  		   A[i]=sc.next();
  	   }
  	   return A;
     }
  static long sum(int A[]) {
  	long sum=0;
  	for(int i : A) {
  		sum+=i;
  	}
  	return sum;
  }
  static long sum(long A[]) {
  	long sum=0;
  	for(long i : A) {
  		sum+=i;
  	}
  	return sum;
  }
  static void reverse(long A[]) {
  	int n=A.length;
  	long B[]=new long[n];
  	for(int i=0;i<n;i++) {
  		B[i]=A[n-i-1];
  	}
  	for(int i=0;i<n;i++)
  		A[i]=B[i];
  	
  }
  static void reverse(int A[]) {
  	int n=A.length;
  	int B[]=new int[n];
  	for(int i=0;i<n;i++) {
  		B[i]=A[n-i-1];
  	}
  	for(int i=0;i<n;i++)
  		A[i]=B[i];
  	
  }
  static void input(int A[],int B[]) {
  	   for(int i=0;i<A.length;i++) {
  		   A[i]=sc.nextInt();
  		   B[i]=sc.nextInt();
  	   }
  }
  static int[][] input(int n,int m){
  	int A[][]=new int[n][m];
  	for(int i=0;i<n;i++) {
  		for(int j=0;j<m;j++) {
  			A[i][j]=i();
  		}
  	}
  	return A;
  }
  static char[][] charinput(int n,int m){
  	char A[][]=new char[n][m];
  	for(int i=0;i<n;i++) {
  		String s=s();
  		for(int j=0;j<m;j++) {
  			A[i][j]=s.charAt(j);
  		}
  	}
  	return A;
  }
  
  static int max(int A[]) {
  	int max=Integer.MIN_VALUE;
  	for(int i=0;i<A.length;i++) {
  		max=Math.max(max, A[i]);
  	}
  	return max;
  }
  static int min(int A[]) {
  	int min=Integer.MAX_VALUE;
  	for(int i=0;i<A.length;i++) {
  		min=Math.min(min, A[i]);
  	}
  	return min;
  }
  static long max(long A[]) {
  	long max=Long.MIN_VALUE;
  	for(int i=0;i<A.length;i++) {
  		max=Math.max(max, A[i]);
  	}
  	return max;
  }
  static long min(long A[]) {
  	long min=Long.MAX_VALUE;
  	for(int i=0;i<A.length;i++) {
  		min=Math.min(min, A[i]);
  	}
  	return min;
  }
  static long [] prefix(long A[]) {
  	long p[]=new long[A.length];
  	p[0]=A[0];
  	for(int i=1;i<A.length;i++)
  		p[i]=p[i-1]+A[i];
  	return p;
  }
  static long [] prefix(int A[]) {
  	long p[]=new long[A.length];
  	p[0]=A[0];
  	for(int i=1;i<A.length;i++)
  		p[i]=p[i-1]+A[i];
  	return p;
  }
  static long [] suffix(long A[]) {
  	long p[]=new long[A.length];
  	p[A.length-1]=A[A.length-1];
  	for(int i=A.length-2;i>=0;i--)
  		p[i]=p[i+1]+A[i];
  	return p;
  }
  static long [] suffix(int A[]) {
  	long p[]=new long[A.length];
  	p[A.length-1]=A[A.length-1];
  	for(int i=A.length-2;i>=0;i--)
  		p[i]=p[i+1]+A[i];
  	return p;
  }
  static void fill(int dp[]) {
  	Arrays.fill(dp, -1);
  }
  static void fill(int dp[][]) {
  	for(int i=0;i<dp.length;i++)
  	Arrays.fill(dp[i], -1);
  }
  static void fill(int dp[][][]) {
  	for(int i=0;i<dp.length;i++) {
  		for(int j=0;j<dp[0].length;j++) {
  			Arrays.fill(dp[i][j],-1);
  		}
  	}
  }
  static void fill(int dp[][][][]) {
  	for(int i=0;i<dp.length;i++) {
  		for(int j=0;j<dp[0].length;j++) {
  			for(int k=0;k<dp[0][0].length;k++) {
  			Arrays.fill(dp[i][j][k],-1);
  			}
  		}
  	}
  }
  static void fill(long dp[]) {
  	Arrays.fill(dp, -1);
  }
  static void fill(long dp[][]) {
  	for(int i=0;i<dp.length;i++)
  	Arrays.fill(dp[i], -1);
  }
  static void fill(long dp[][][]) {
  	for(int i=0;i<dp.length;i++) {
  		for(int j=0;j<dp[0].length;j++) {
  			Arrays.fill(dp[i][j],-1);
  		}
  	}
  }
  static void fill(long dp[][][][]) {
  	for(int i=0;i<dp.length;i++) {
  		for(int j=0;j<dp[0].length;j++) {
  			for(int k=0;k<dp[0][0].length;k++) {
  			Arrays.fill(dp[i][j][k],-1);
  			}
  		}
  	}
  }
  static int min(int a,int b) {
  	return Math.min(a, b);
  }
  static int min(int a,int b,int c) {
  	return Math.min(a, Math.min(b, c));
  }
  static int min(int a,int b,int c,int d) {
  	return Math.min(a, Math.min(b, Math.min(c, d)));
  }
  static int max(int a,int b) {
  	return Math.max(a, b);
  }
  static int max(int a,int b,int c) {
  	return Math.max(a, Math.max(b, c));
  }
  static int max(int a,int b,int c,int d) {
  	return Math.max(a, Math.max(b, Math.max(c, d)));
  }
  static long min(long a,long b) {
  	return Math.min(a, b);
  }
  static long min(long a,long b,long c) {
  	return Math.min(a, Math.min(b, c));
  }
  static long min(long a,long b,long c,long d) {
  	return Math.min(a, Math.min(b, Math.min(c, d)));
  }
  static long max(long a,long b) {
  	return Math.max(a, b);
  }
  static long max(long a,long b,long c) {
  	return Math.max(a, Math.max(b, c));
  }
  static long max(long a,long b,long c,long d) {
  	return Math.max(a, Math.max(b, Math.max(c, d)));
  }
  
  static long power(long x, long y, long p)
  {
  
  	if(y==0)
  		return 1;
  	if(x==0)
  		return 0;
      long res = 1;
      x = x % p;
  
      while (y > 0) {
  
          if (y % 2 == 1)
              res = (res * x) % p;
  
          y = y >> 1; 
          x = (x * x) % p;
      }
  
      return res;
  }
  static long power(long x, long y)
  {
  
  	if(y==0)
  		return 1;
  	if(x==0)
  		return 0;
      long res = 1;
  
      while (y > 0) {
  
          if (y % 2 == 1)
              res = (res * x);
  
          y = y >> 1; 
          x = (x * x);
      }
  
      return res;
  }
  static void print(int A[]) {
  	for(int i : A) {
  		System.out.print(i+" ");
  	}
  	System.out.println();
  }
  static void print(long A[]) {
  	for(long i : A) {
  		System.out.print(i+" ");
  	}
  	System.out.println();
  }
  static long mod(long x) {
  	  return ((x%mod + mod)%mod);
  }
  static String reverse(String s) {
  	StringBuffer p=new StringBuffer(s);
  	p.reverse();
  	return p.toString();
  }
  
       static int i() {
      	 return sc.nextInt();
       }
       static String s() {
      	 return sc.next();
       }
       static long l() {
      	 return sc.nextLong();
       }  
       static void sort(int[] A){
          int n = A.length;
          Random rnd = new Random();
          for(int i=0; i<n; ++i){
              int tmp = A[i];
              int randomPos = i + rnd.nextInt(n-i);
              A[i] = A[randomPos];
              A[randomPos] = tmp;
          }
          Arrays.sort(A);
       }
       static void sort(long[] A){
  	        int n = A.length;
  	        Random rnd = new Random();
  	        for(int i=0; i<n; ++i){
  	            long tmp = A[i];
  	            int randomPos = i + rnd.nextInt(n-i);
  	            A[i] = A[randomPos];
  	            A[randomPos] = tmp;
  	        }
  	        Arrays.sort(A);
  	     }
    static String sort(String s) {
   	 Character ch[]=new Character[s.length()];
   	 for(int i=0;i<s.length();i++) {
   		 ch[i]=s.charAt(i);
   	 }
   	 Arrays.sort(ch);
   	 StringBuffer st=new StringBuffer("");
   	 for(int i=0;i<s.length();i++) {
   		 st.append(ch[i]);
   	 }
   	 return st.toString();
    }
    static HashMap<Integer,Integer> hash(int A[]){
  	  HashMap<Integer,Integer> map=new HashMap<Integer, Integer>();
  	  for(int i : A) {
  		  if(map.containsKey(i)) {
  			  map.put(i, map.get(i)+1);
  		  }
  		  else {
  			  map.put(i, 1);
  		  }
  	  }
  	  return map;
    }
    static TreeMap<Integer,Integer> tree(int A[]){
  	  TreeMap<Integer,Integer> map=new TreeMap<Integer, Integer>();
  	  for(int i : A) {
  		  if(map.containsKey(i)) {
  			  map.put(i, map.get(i)+1);
  		  }
  		  else {
  			  map.put(i, 1);
  		  }
  	  }
  	  return map;
    }
       static boolean prime(int n) 
  	    { 
  	        if (n <= 1) 
  	            return false; 
  	        if (n <= 3) 
  	            return true; 
  	        if (n % 2 == 0 || n % 3 == 0) 
  	            return false; 
  	        double sq=Math.sqrt(n);
  	  
  	        for (int i = 5; i <= sq; i = i + 6) 
  	            if (n % i == 0 || n % (i + 2) == 0) 
  	                return false; 
  	        return true; 
  	    } 
       static boolean prime(long n) 
  	    { 
  	        if (n <= 1) 
  	            return false; 
  	        if (n <= 3) 
  	            return true; 
  	        if (n % 2 == 0 || n % 3 == 0) 
  	            return false; 
  	        double sq=Math.sqrt(n);
  	  
  	        for (int i = 5; i <= sq; i = i + 6) 
  	            if (n % i == 0 || n % (i + 2) == 0) 
  	                return false; 
  	        return true; 
  	    } 
       static int gcd(int a, int b) 
       { 
           if (a == 0) 
               return b; 
           return gcd(b % a, a); 
       } 
       static long gcd(long a, long b) 
       { 
           if (a == 0) 
               return b; 
           return gcd(b % a, a); 
       } 
       
          
      static class FastReader 
      { 
          BufferedReader br; 
          StringTokenizer st; 
    
          public FastReader() 
          { 
              br = new BufferedReader(new
                       InputStreamReader(System.in)); 
          } 
    
          String next() 
          { 
              while (st == null || !st.hasMoreElements()) 
              { 
                  try
                  { 
                      st = new StringTokenizer(br.readLine()); 
                  } 
                  catch (IOException  e) 
                  { 
                      e.printStackTrace(); 
                  } 
              } 
              return st.nextToken(); 
          } 
    
          int nextInt() 
          { 
              return Integer.parseInt(next()); 
          } 
    
          long nextLong() 
          { 
              return Long.parseLong(next()); 
          } 
    
          double nextDouble() 
          { 
              return Double.parseDouble(next()); 
          } 
    
          String nextLine() 
          { 
              String str = ""; 
              try
              { 
                  str = br.readLine(); 
              } 
              catch (IOException e) 
              { 
                  e.printStackTrace(); 
              } 
              return str; 
          } 
      } 
  } 
  
  
  
  