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.ArrayList;
  import java.util.HashSet;
  import java.util.LinkedList;
  import java.util.Queue;
  import java.io.BufferedReader;
  import java.io.FileReader;
  import java.io.IOException;
  import java.io.InputStreamReader;
  import java.util.StringTokenizer;
  import java.util.Arrays;
  import java.util.Random;
  import java.io.FileWriter;
  import java.io.PrintWriter;
  /*
      Solution Created: 20:55:56 08/10/2021
      Custom Competitive programming helper.
  */
  
  public class Main {
  	static int n, m;
  	static ArrayList<Edge> adj[];
  	static int ans = 0;
  	static HashSet<Integer> toBeVisited;
  	static boolean can;
  	static HashSet<Integer> s1, s2;
  	static boolean[] vis;
  	public static void solve() {
  		n = in.nextInt(); m = in.nextInt();
  		adj = new ArrayList[n];
  		for(int i = 0; i<n; i++) adj[i] = new ArrayList<>();
  		toBeVisited = new HashSet<>();
  		can = true;
  		for(int i = 0; i<m; i++) {
  			int u = in.nextInt()-1, v = in.nextInt()-1;
  			boolean imp = in.next().equals("imposter");
  			adj[u].add(new Edge(v, imp));
  			adj[v].add(new Edge(u, imp));
  		}
  		vis = new boolean[n];
  		int ans = 0;
  		for(int i = 0; i<n && can; i++) {
  			if(vis[i]) continue;
  			int[] v = startFromNode(i);
  			Util.sortArray(v);
  			ans += v[1];
  		}
  		if(!can) {
  			out.println(-1);
  			return;
  		}
  		out.println(ans);
  		
  	}
  	static int[] startFromNode(int i) {
  		s1 = new HashSet<>();
  		s2 = new HashSet<>();
  		dfs(i, true);
  		return new int[] {s1.size(),s2.size()};
  	}
  	static void dfs(int i, boolean good) {
  		vis[i] = true;
  		if(isDefined(i)) {
  			if(isGood(i) != good) can = false;
  			return;
  		}
  		if(good) setGood(i);
  		else setBad(i);
  		for(Edge e : adj[i]) {
  			int j = e.v;
  			boolean sayGood = !e.impostor;
  			boolean otherGood = !(sayGood^good);
  			dfs(j, otherGood);
  		}
  	}
  	
  	public static void setGood(int i) {
  		s1.add(i);
  	}
  	public static void setBad(int i) {
  		s2.add(i);
  	}
  	public static boolean isDefined(int i) {
  		return s1.contains(i) || s2.contains(i);
  	}
  	public static boolean isGood(int i) {
  		if(s1.contains(i)) return true;
  		return false;
  	}
  	static class Edge {
  		int v;
  		boolean impostor;
  		public Edge(int v, boolean i) {
  			this.v = v;
  			this.impostor = i;
  		}
  	}
  
  	public static void main(String[] args) {
  		in = new Reader();
  		out = new Writer();
  		int t = in.nextInt();
  		while (t-- > 0)
  			solve();
  		out.exit();
  	}
  
  	static Reader in;
  	static Writer out;
  
  static class Reader {
  	static BufferedReader br;
  	static StringTokenizer st;
  	
  	public Reader() {
  		this.br = new BufferedReader(new InputStreamReader(System.in));
  	}
  	
  	public Reader(String f){
  		try {
  			this.br = new BufferedReader(new FileReader(f));
  		} catch (IOException e) {
  			e.printStackTrace();
  		}
  	}
  	
  	public int[] na(int n) {
  		int[] a = new int[n];
  		for (int i = 0; i < n; i++) a[i] = nextInt();
  		return a;
  	}
  
  	public double[] nd(int n) {
  		double[] a = new double[n];
  		for (int i = 0; i < n; i++) a[i] = nextDouble();
  		return a;
  	}
  	
  	public long[] nl(int n) {
  		long[] a = new long[n];
  		for (int i = 0; i < n; i++) a[i] = nextLong();
  		return a;
  	}
  
  	public char[] nca() {
  		return next().toCharArray();
  	}
  
  	public String[] ns(int n) {
  		String[] a = new String[n];
  		for (int i = 0; i < n; i++) a[i] = next();
  		return a;
  	}
  
  	public int nextInt() {
  		ensureNext();
  		return Integer.parseInt(st.nextToken());
  	}
  
  	public double nextDouble() {
  		ensureNext();
  		return Double.parseDouble(st.nextToken());
  	}
  
  	public Long nextLong() {
  		ensureNext();
  		return Long.parseLong(st.nextToken());
  	}
  
  	public String next() {
  		ensureNext();
  		return st.nextToken();
  	}
  	
  	public String nextLine() {
  		try {
  			return br.readLine();
  		} catch (Exception e) {
  			e.printStackTrace();
  			return null;
  		}
  	}
  	
  	private void ensureNext() {
  		if (st == null || !st.hasMoreTokens()) {
  			try {
  				st = new StringTokenizer(br.readLine());
  			} catch (IOException e) {
  				e.printStackTrace();
  			}
  		}
  	}
  }
  
  static class Util{
  		private static Random random = new Random();
  		static long[] fact;
  		
  		public static void initFactorial(int n, long mod) {
  			fact = new long[n+1];
  			fact[0] = 1;
  			for (int i = 1; i < n+1; i++) fact[i] = (fact[i - 1] * i) % mod;
  		}
  		
  		public static long modInverse(long a, long MOD) {
  			long[] gcdE = gcdExtended(a, MOD);
  			if (gcdE[0] != 1) return -1; // Inverted doesn't exist
  			long x = gcdE[1];
  			return (x % MOD + MOD) % MOD;
  		}
  		
  		public static long[] gcdExtended(long p, long q) {
  			if (q == 0) return new long[] { p, 1, 0 };
  			long[] vals = gcdExtended(q, p % q);
  			long tmp = vals[2];
  			vals[2] = vals[1] - (p / q) * vals[2];
  			vals[1] = tmp;
  			return vals;
  		}
  		
  		public static long nCr(int n, int r, long MOD) {
  			if (r == 0) return 1;
  			return (fact[n] * modInverse(fact[r], MOD) % MOD * modInverse(fact[n - r], MOD) % MOD) % MOD;
  		}
  		
  		public static long nCr(int n, int r) {
  			return (fact[n]/fact[r])/fact[n-r];
  		}
  		
  		public static long nPr(int n, int r, long MOD) {
  			if (r == 0) return 1;
  			return (fact[n] * modInverse(fact[n - r], MOD) % MOD) % MOD;
  		}
  		public static long nPr(int n, int r) {
  			return fact[n]/fact[n-r];
  		}
  		
  		public 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; 
  	    }
  		
  	    public static boolean[] getSieve(int n) {
  	        boolean[] isPrime = new boolean[n+1];
  	        for (int i = 2; i <= n; i++) isPrime[i] = true;
  	        for (int i = 2; i*i <= n; i++) if (isPrime[i]) 
  	                for (int j = i; i*j <= n; j++) isPrime[i*j] = false;
  	        return isPrime;
  	    }
  	    
  	    static long pow(long x, long pow, long mod){
  	    	long res = 1;
  	    	x = x % mod;
  	    	if (x == 0) return 0;
  	    	while (pow > 0){
  	    		if ((pow & 1) != 0) res = (res * x) % mod;
  	        	pow >>= 1;
  	        	x = (x * x) % mod;
  	    	}
  	    	return res;
  	    }
  	    
  	    public static int gcd(int a, int b) { 
  	    	int tmp = 0;
  	    	while(b != 0) {
  	    		tmp = b;
  	    		b = a%b;
  	    		a = tmp;
  	    	}
  	    	return a;
  	    }
  	    
  	    public static long gcd(long a, long b) { 
  	    	long tmp = 0;
  	    	while(b != 0) {
  	    		tmp = b;
  	    		b = a%b;
  	    		a = tmp;
  	    	}
  	    	return a;
  	    }
  	    
  	    public static int random(int min, int max) {
  	    	return random.nextInt(max-min+1)+min;
  	    }
  	    
  		public static void dbg(Object... o) { 
  			System.out.println(Arrays.deepToString(o)); 
  		}
  		
  		public static void reverse(int[] s, int l , int r) {
  			for(int i = l; i<=(l+r)/2; i++) {
  				int tmp = s[i];
  				s[i] = s[r+l-i];
  				s[r+l-i] = tmp;
  			}
  	    }
  		
  		public static void reverse(int[] s) {
  			reverse(s, 0, s.length-1);
  	    }
  		
  		public static void reverse(long[] s, int l , int r) {
  			for(int i = l; i<=(l+r)/2; i++) {
  				long tmp = s[i];
  				s[i] = s[r+l-i];
  				s[r+l-i] = tmp;
  			}
  	    }
  		
  		public static void reverse(long[] s) {
  			reverse(s, 0, s.length-1);
  	    }
  		
  		public static void reverse(float[] s, int l , int r) {
  			for(int i = l; i<=(l+r)/2; i++) {
  				float tmp = s[i];
  				s[i] = s[r+l-i];
  				s[r+l-i] = tmp;
  			}
  	    }
  		
  		public static void reverse(float[] s) {
  			reverse(s, 0, s.length-1);
  	    }
  		
  		public static void reverse(double[] s, int l , int r) {
  			for(int i = l; i<=(l+r)/2; i++) {
  				double tmp = s[i];
  				s[i] = s[r+l-i];
  				s[r+l-i] = tmp;
  			}
  	    }
  		
  		public static void reverse(double[] s) {
  			reverse(s, 0, s.length-1);
  	    }
  		
  		public static void reverse(char[] s, int l , int r) {
  			for(int i = l; i<=(l+r)/2; i++) {
  				char tmp = s[i];
  				s[i] = s[r+l-i];
  				s[r+l-i] = tmp;
  			}
  	    }
  		
  		public static void reverse(char[] s) {
  			reverse(s, 0, s.length-1);
  	    }
  		
  		public static <T> void reverse(T[] s, int l , int r) {
  			for(int i = l; i<=(l+r)/2; i++) {
  				T tmp = s[i];
  				s[i] = s[r+l-i];
  				s[r+l-i] = tmp;
  			}
  	    }
  		
  		public static <T> void reverse(T[] s) {
  			reverse(s, 0, s.length-1);
  	    }
  		
  		public static void shuffle(int[] s) {
  	        for (int i = 0; i < s.length; ++i) {
  	            int j = random.nextInt(i + 1);
  	            int t = s[i];
  	            s[i] = s[j];
  	            s[j] = t;
  	        }
  	    }
  		
  	    public static void shuffle(long[] s) {
  	        for (int i = 0; i < s.length; ++i) {
  	            int j = random.nextInt(i + 1);
  	            long t = s[i];
  	            s[i] = s[j];
  	            s[j] = t;
  	        }
  	    }
  	    
  	    public static void shuffle(float[] s) {
  	        for (int i = 0; i < s.length; ++i) {
  	            int j = random.nextInt(i + 1);
  	            float t = s[i];
  	            s[i] = s[j];
  	            s[j] = t;
  	        }
  	    }
  	    
  	    public static void shuffle(double[] s) {
  	        for (int i = 0; i < s.length; ++i) {
  	            int j = random.nextInt(i + 1);
  	            double t = s[i];
  	            s[i] = s[j];
  	            s[j] = t;
  	        }
  	    }
  	    
  	    public static void shuffle(char[] s) {
  	        for (int i = 0; i < s.length; ++i) {
  	            int j = random.nextInt(i + 1);
  	            char t = s[i];
  	            s[i] = s[j];
  	            s[j] = t;
  	        }
  	    }
  	    
  	    public static <T> void shuffle(T[] s) {
  	        for (int i = 0; i < s.length; ++i) {
  	            int j = random.nextInt(i + 1);
  	            T t = s[i];
  	            s[i] = s[j];
  	            s[j] = t;
  	        }
  	    }
  	    
  		public static void sortArray(int[] a) {
  	        shuffle(a);
  	        Arrays.sort(a);
  	    }
  		
  		public static void sortArray(long[] a) {
  			shuffle(a);
  	        Arrays.sort(a);
  	    }
  		
  		public static void sortArray(float[] a) {
  			shuffle(a);
  	        Arrays.sort(a);
  	    }
  		
  		public static void sortArray(double[] a) {
  			shuffle(a);
  	        Arrays.sort(a);
  	    }
  		
  		public static void sortArray(char[] a) {
  			shuffle(a);
  	        Arrays.sort(a);
  	    }
  		
  		public static <T extends Comparable<T>> void sortArray(T[] a) {
  	        Arrays.sort(a);
  	    }
  	}
  
  static class Writer {
  	private PrintWriter pw;
  	public Writer(){
  		pw = new PrintWriter(System.out);
  	}
  	
  	public Writer(String f){
  		try {
  			pw = new PrintWriter(new FileWriter(f));
  		} catch (IOException e) {
  			e.printStackTrace();
  		}
  	}
  	
  	public void yesNo(boolean condition) {
  		println(condition?"YES":"NO");
  	}
  	
  	public void printArray(int[] a) {
  		for(int i = 0; i<a.length; i++) print(a[i]+" ");
  	}
  	
  	public void printlnArray(int[] a) {
  		for(int i = 0; i<a.length; i++) print(a[i]+" ");
  		pw.println();
  	}
  	
  	public void printArray(long[] a) {
  		for(int i = 0; i<a.length; i++) print(a[i]+" ");
  	}
  	
  	public void printlnArray(long[] a) {
  		for(int i = 0; i<a.length; i++) print(a[i]+" ");
  		pw.println();
  	}
  	
  	public void print(Object o) {
  		pw.print(o.toString());
  	}
  	
  	public void println(Object o) {
  		pw.println(o.toString());
  	}
  	
  	public void println() {
  		pw.println();
  	}
  	
  	public void flush() {
  		pw.flush();
  	}
  	public void exit() {
  		pw.close();
  	}
  }
  }
  