Untitled

import java.io.*;
import java.util.*;

public class Solution {
    public static void DFS(ArrayList[] graph,boolean[] vis,int s){
        if(vis[s]=true) return;
        vis[s]=true;
        ArrayList<Integer> al=graph[s];
        for(int ele:al){
            DFS(graph,vis,ele);
        }
    }
    public static void main(String[] args) throws IOException{
        /* Enter your code here. Read input from STDIN. Print output to STDOUT. Your class should be named Solution. */
        BufferedReader br=new BufferedReader(new InputStreamReader(System.in));
        BufferedWriter bw=new BufferedWriter(new OutputStreamWriter(System.out));
        int tc=Integer.parseInt(br.readLine());
        while(tc-->0){
            String[] in=br.readLine().split(" ");
            int n=Integer.parseInt(in[0]);
            int m=Integer.parseInt(in[1]);
            ArrayList[] a=new ArrayList[n+1];
            boolean[] vis=new boolean[n+1];
            for(int i=0;i<n+1;i++){
                vis[i]=false;
            }
            while(m-->0){
                String[] s=br.readLine().split(" ");
                int x=Integer.parseInt(s[0]);
                int y=Integer.parseInt(s[1]);
                a[x].add(y);
            }
            int c=0;
            for(int i=0;i<n+1;i++){
                if(vis[i]==false){
                    DFS(a,vis,i);
                    c++;
                }
            }
            bw.write(c+"\n");
        }
        bw.flush();
    }
}