SCC

// { Driver Code Starts
#include<bits/stdc++.h>
using namespace std;

 // } Driver Code Ends



class Solution
{
    private:
    vector<bool> visited;
    stack<int> st;

    void dfs(int u, vector<int> adj[])
    {
        visited[u] = 1;
        for (auto v : adj[u])
        {
            if (!visited[v])
            {
                dfs(v, adj);
            }
        }
        st.push(u);
    }

    void dfs2(int u, vector<int> adj[]){
        visited[u]=1;

        for(auto v:adj[u]){
            if(!visited[v]){
                dfs2(v, adj);
            }
        }
    }

    // vector<vector<int>> reverseGraph(vector<int> adj[], int n)
    // {
       // vector<vector<int>> rev(n);
       // for (int i = 0; i < n; i++)
       // {
          //  for (auto v : adj[i])
          //  {
             //   rev[v].push_back(i);
          //  }
       // }
       // return rev;
    // }



    public:
    //Function to find number of strongly connected components in the graph.
    int kosaraju(int V, vector<int> adj[])
    {
        //code here
        int n = V, ans = 0;
        visited.assign(n, false);
        for (int i = 0; i < n; i++)
        {
            if (!visited[i])
            {
                dfs(i, adj);
            }
        }

        visited.assign(n, false);
       // auto revAdj = reverseGraph(adj, n);

       vector<int> revAdj[n];

       for(int i=0;i<n;i++){
           for(auto v: adj[i]){
               revAdj[v].push_back(i);
           }
       }

        while(!st.empty()){
            int s = st.top();
            st.pop();

            if(!visited[s]){
                ans++;
                for(auto v: revAdj[s]){
                    if(!visited[v]){
                        dfs2(v, revAdj);
                    }
                }
            }

        }

        return ans;
    }
};

// { Driver Code Starts.


int main()
{

    int t;
    cin >> t;
    while(t--)
    {
        int V, E;
        cin >> V >> E;

        vector<int> adj[V];

        for(int i = 0; i < E; i++)
        {
            int u, v;
            cin >> u >> v;
            adj[u].push_back(v);
        }

        Solution obj;
        cout << obj.kosaraju(V, adj) << "\n";
    }

    return 0;
}

  // } Driver Code Ends