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.*;
  
  
  
  public class Main {
  	  static class Reader{
  		  
  			BufferedReader br;
  			StringTokenizer st;
  			public Reader() {
  				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; 
  		    } 
  		}
  	 
  	  static long mod = (long)(1e9 + 7);
  	 
  	static void sort(long[] arr ) {
  		 ArrayList<Long> al = new ArrayList<>();
  		 for(long e:arr) al.add(e);
  		 Collections.sort(al);
  		 for(int i = 0 ; i<al.size(); i++) arr[i] = al.get(i);
  	 }
  	static void sort(int[] arr ) {
  		 ArrayList<Integer> al = new ArrayList<>();
  		 for(int e:arr) al.add(e);
  		 Collections.sort(al);
  		 for(int i = 0 ; i<al.size(); i++) arr[i] = al.get(i);
  	 }
  	static void sort(char[] arr) {
  		ArrayList<Character> al = new ArrayList<Character>();
  		for(char cc:arr) al.add(cc);
  		Collections.sort(al);
  		for(int i = 0 ;i<arr.length ;i++) arr[i] = al.get(i);
  	}
  	static void rvrs(int[] arr) {
  		int i =0 , j = arr.length-1;
  		while(i>=j) {
  			int temp = arr[i];
  			arr[i] = arr[j];
  			arr[j] = temp;
  			i++;
  			j--;
  		}
  	}
  	static long[] rvrs(long[] arr) {
  		int i =0 , j = arr.length-1;
  		int n = arr.length;
  		long[] ans = new long[n];
  		for( i =0 ; i<n ; i++)
  			ans[i] = arr[j--];
  		return ans;
  	}
  
  	static long mod_mul(long a , long b ,long mod) {
  		return ((a%mod)*(b%mod))%mod;
  	}
  	 static long gcd(long a, long b)
  	  {      
  	     if (b == 0)
  	        return a;
  	     return gcd(b, a % b); 
  	  }
  	 static boolean[] prime(int num) {
  			boolean[] bool = new boolean[num];
  		     
  		      for (int i = 0; i< bool.length; i++) {
  		         bool[i] = true;
  		      }
  		      for (int i = 2; i< Math.sqrt(num); i++) {
  		         if(bool[i] == true) {
  		            for(int j = (i*i); j<num; j = j+i) {
  		               bool[j] = false;
  		            }
  		         }
  		      }
  		      if(num >= 0) {
  		    	  bool[0] = false;
  		    	  bool[1] = false;
  		      }
  		      
  		      return bool;
  		}
  
  	 static long modInverse(long a, long m)
  	    {
  	        long g = gcd(a, m);
  	       
  	          return   power(a, m - 2, m);
  	        
  	    }
  	   
  	 static long power(long x, long y, long m){
  	        if (y == 0) return 1; long p = power(x, y / 2, m) % m; p = (int)((p * (long)p) % m);
  	        if (y % 2 == 0) return p; else return (int)((x * (long)p) % m); }
  	   
       static class Combinations{
  	    	 private long[] z;
  	    	 private long[] z1;
  	    	 private long[] z2;
  	    	 long MOD;
  	    	  public Combinations(long N , long mod) {
  	    		  MOD  = mod;
  				z = new long[(int)N+1];
  				z1 = new long[(int)N+1];
  				z[0] = 1;
  				for(int i =1 ; i<=N ; i++) z[i] = (z[i-1]*i)%MOD;
  			     z2 = new long[(int)N+1];
  				z2[0] = z2[1] = 1;
  			    for (int i = 2; i <= N; i++)
  			        z2[i] = z2[(int)(MOD % i)] * (MOD - MOD / i) % MOD;
  			    
  			    
  			    z1[0] = z1[1] = 1;
  			    
  			    for (int i = 2; i <= N; i++)
  			        z1[i] = (z2[i] * z1[i - 1]) % MOD;
  			}
  	    	  long fac(long n) {
  	    		  return z[(int)n];
  	    	  }
  	    	  long invrsNum(long n) {
  	    		  return z2[(int)n];
  	    	  }
  	    	  long invrsFac(long n) {
  	    		  return invrsFac((int)n);
  	    	  }
  	    	  long ncr(long N, long R)
  	    	  {		if(R<0 || R>N ) return 0;
  	    		    long ans = ((z[(int)N] * z1[(int)R])
  	    		              % MOD * z1[(int)(N - R)])
  	    		             % MOD;
  	    		    return ans;
  	    		}
  	      }
       static class DisjointUnionSets {
           private int[] parent;  // parent[i] = parent of i
           private byte[] rank;   // rank[i] = rank of subtree rooted at i (never more than 31)
           private int count;     // number of components
           private int[] size;
           public DisjointUnionSets(int n) {
               if (n < 0) throw new IllegalArgumentException();
               count = n;
               parent = new int[n];
               rank = new byte[n];
               size = new int[n];
               for (int i = 0; i < n; i++) {
                   parent[i] = i;
                   rank[i] = 0;
                   size[i] = 1;
               }
           }
    
           public int find(int p) {
               while (p != parent[p]) {
                   parent[p] = parent[parent[p]];    // path compression by halving
                   p = parent[p];
               }
               return p;
           }
    
           public int count() {
               return count;
           }
    
           public boolean connected(int p, int q) {
               return find(p) == find(q);
           }
    
           public void union(int p, int q) {
               int rootP = find(p);
               int rootQ = find(q);
               if (rootP == rootQ) return;
    
               // make root of smaller rank point to root of larger rank
               if (rank[rootP] < rank[rootQ]) {
                   parent[rootP] = rootQ;
                   size[rootQ] = size[rootQ] + size[rootP];
               }
               else if (rank[rootP] > rank[rootQ]) {
                   parent[rootQ] = rootP;
                   size[rootP] = size[rootP] + size[rootQ];
               }
               else {
                   parent[rootQ] = rootP;
                   size[rootP] = size[rootP] + size[rootQ];
                   rank[rootP]++;
               }
               count--;
           }
       }
  	      static int[] KMP(String str) {
  	    	  int n = str.length();
  	    	  int[] kmp = new int[n];
  	    	  for(int i = 1 ; i<n ; i++) {
  	    		  int j = kmp[i-1];
  	    		  while(j>0 && str.charAt(i) != str.charAt(j)) {
  	    			  j = kmp[j-1];
  	    		  }
  	    		  if(str.charAt(i) == str.charAt(j)) j++;
  	    		  kmp[i] = j;
  	    	  }
  	    	  
  	    	  return kmp;
  	      }
  	      
  	      
  /************************************************ Query **************************************************************************************/	  
  	 
  /***************************************** 		Sparse Table	********************************************************/
  	      static class SparseTable{
  	    		
  	    		private long[][] st;
  	    		
  	    		SparseTable(long[] arr){
  	    			int n = arr.length;
  	    			st = new long[n][25];
  	    			log = new int[n+2];
  	    			build_log(n+1);
  	    			build(arr);
  	    		}
  	    		
  	    		private void build(long[] arr) {
  	    			int n = arr.length;
  	    			
  	    			for(int i = n-1 ; i>=0 ; i--) {
  	    				for(int j = 0 ; j<25 ; j++) {
  	    					int r = i + (1<<j)-1;
  	    					if(r>=n) break;
  	    					if(j == 0 ) st[i][j] = arr[i];
  	    					else st[i][j] = Math.min(st[i][j-1] , st[ i + ( 1 << (j-1) ) ][ j-1 ] );
  	    				}
  	    			}
  	    		}
  	    		public long gcd(long a  ,long b) {
  	    			if(a == 0) return b;
  	    			return gcd(b%a , a);
  	    		}
  	    		public long query(int l ,int r) {
  	    			
  	    			int w = r-l+1;
  	    			int power = log[w];
  	    			return Math.min(st[l][power],st[r - (1<<power) + 1][power]);
  	    		}
  	    		private int[] log;
  	    		void build_log(int n) {
  	    			log[1] = 0;
  	    			for(int i = 2 ; i<=n ; i++) {
  	    				log[i] = 1 + log[i/2];
  	    			}
  	    		}
  	    	}
  	      
  	      
  /********************************************************	Segement Tree	*****************************************************/
  /**
  	 	 static class SegmentTree{
  			 long[] tree;
  			 long[] arr;
  			 int n;
  			 SegmentTree(long[] arr){
  				 this.n = arr.length;
  				 tree = new long[4*n+1];
  				 this.arr = arr;
  				 buildTree(0, n-1, 1);
  			 }
  			 
  			 
  			  void buildTree(int s ,int e  ,int index ) {
  					if(s == e) {
  						tree[index] = arr[s];
  						return;
  					}
  				
  					int mid = (s+e)/2;
  					
  					buildTree( s,  mid, 2*index);
  					buildTree( mid+1, e, 2*index+1);
  					
  					tree[index] = Math.min(tree[2*index] , tree[2*index+1]);
  				}
  			  
  			 long query(int si ,int ei) {
  				 return query(0 ,n-1 , si ,ei , 1   );
  			 }
  			 private long query( int ss ,int se ,int qs , int qe,int index) {
  					
  					if(ss>=qs && se<=qe) return tree[index];
  					
  					if(qe<ss || se<qs) return (long)(1e17);
  					
  					int mid = (ss + se)/2;
  					long left = query( ss , mid , qs ,qe , 2*index);
  					long right= query(mid + 1 , se , qs ,qe , 2*index+1);
  					return Math.min(left, right);
  				}
  			 public void update(int index , int val) {
  				 arr[index] = val;
  				 for(long e:arr) System.out.print(e+" ");
  				 update(index , 0 , n-1 , 1);
  			 }
  			 private void update(int id ,int si , int ei , int index) {
  				 if(id < si || id>ei) return;
  				 if(si == ei ) { 
  					 tree[index] = arr[id];
  					 return;
  				 }
  				 if(si > ei) return;
  				 int mid = (ei + si)/2;
  					
  					update( id,  si, mid , 2*index);
  					update( id , mid+1, ei , 2*index+1);
  					
  					tree[index] = Math.min(tree[2*index] ,tree[2*index+1]);
  			 }
  			  
  		 }
  		 */
  
  /* ***************************************************************************************************************************************************/	 
  	 
  	      static Reader sc = new Reader();
  	 static StringBuilder sb = new StringBuilder();
  	 public static void main(String args[])  {
  	
  		 int tc = 1;
  		  tc = sc.nextInt();
  		 
  		  for(int i = 1 ; i<=tc ; i++) {
  
  //			 sb.append("Case #" + i + ": "  );	// During KickStart && HackerCup
  			 TEST_CASE();
  			 
  		 }
  		 System.out.println(sb);
  
  	 }
  
  	static void TEST_CASE() {
  		int n = sc.nextInt() , m = sc.nextInt();
  		DisjointUnionSets dsu = new DisjointUnionSets(n+1);
  		adj = new ArrayList<>();
  		for(int i =0 ; i<=n ; i++) adj.add(new ArrayList<>());
  		ArrayList<Pair> imp = new ArrayList<>();
  		ArrayList<Pair> crew= new ArrayList<>();
  		for(int i =0 ;  i<m ; i++) {
  			int x = sc.nextInt()-1 , y = sc.nextInt()-1;
  			String str = sc.next();
  			Pair np = new Pair(x , y);
  			if(str.equals("imposter")) imp.add(np);
  			else crew.add(np);
  		}
  		for(Pair pp:crew) {
  			dsu.union(pp.x, pp.y);
  		}
  		int[] p = new int[n+1];
  		int[] connect = new int[n+1];
  		for(int i = 0 ; i<n ; i++) {
  			p[i] = dsu.find(i);
  			connect[p[i]]++;
  		}
  		Set<Pair> set = new HashSet<>();
  		for(Pair pp:imp) {
  			int p1 = p[pp.x];
  			int p2 = p[pp.y];
  			if(p1 == p2) {
  				sb.append("-1\n");
  				return;
  			}
  			if(set.contains(new Pair(p1,p2))) continue;
  			set.add(new Pair(p1 , p2));
  			set.add(new Pair(p2 , p1));
  			adj.get(p1).add(p2);
  			adj.get(p2).add(p1);
  		}
  		int ans = 0;
  		boolean[] visit = new boolean[n+1];
  //		System.out.println(adj);
  		int[] col = new int[n+1];
  		for(int i = 0 ; i<n ; i++) {
  			if(visit[i]) continue;
  			zc = 0 ; oc = 0;
  			if(dfs(i, -1, col, 0, visit, connect)) {
  				sb.append("-1\n");
  				return;
  			}
  			ans += Math.max(zc, oc);
  		}
  		sb.append(ans+"\n");
   	}
  	static ArrayList<ArrayList<Integer>> adj;
  	static int zc , oc;
  	
  	static boolean dfs(int u ,int p ,int[] col ,int c , boolean[] visit , int[] connect) {
  		if(visit[u]) {
  			if(col[u] != c) return true;
  			else return false;
  		}
  		
  		visit[u] = true;
  		col[u] = c;
  		if(c == 1) {
  			oc += connect[u]; 
  		}else {
  			zc += connect[u];
  		}
  		for(int v:adj.get(u)) {
  			if(!visit[v]) {
  				if(dfs(v, u, col, 1-c, visit, connect))
  					return true;
  			}else if(v != p && col[v] == c) {
  				return true;
  				
  			}
  		}
  		
  		return false;
  	}
  	
  	
  	static class Pair{
  		int x,y;
  		Pair(int x , int y){
  			this.x = x;
  			this.y = y;
  		}
  		
  		@Override
  		public boolean equals(Object obj) {
  			if (this == obj)
  				return true;
  			if (obj == null)
  				return false;
  			if (getClass() != obj.getClass())
  				return false;
  			Pair other = (Pair) obj;
  			if (x != other.x)
  				return false;
  			if (y != other.y)
  				return false;
  			return true;
  		}
  
  		@Override
  		public int hashCode() {
  			 return Objects.hash(x, y);
  		}
  	}
  }
  
  /*******************************************************************************************************************************************************/
  
  /**
  
   */
  
  
  
  
  
  
  