#include <iostream>
#include <vector>
#include <algorithm>
#include <string>
#include <cstring>
#include <stack>
#include <queue>
#include <cmath>
#include <set>
#include <map>
#include <cassert>
#define fast_io cin.tie(NULL); ios_base::sync_with_stdio(false);
using namespace std;
typedef long long ll;
typedef pair<int, int> pii;
typedef pair<ll, ll> pll;

const int MAX = 100001;
int n, m;
vector<int> G[MAX], R[MAX],DAG[MAX], C, order;
vector<bool> visited;

void DFS1(int here){
    C[here] = -1;
    for(int next : G[here]){
        if(!C[next]) DFS1(next);
    }
    order.push_back(here);
}

void DFS2(int here, int color){
    C[here] = color;
    for(int next : R[here]){
        if(C[next]==-1) DFS2(next, color);
    }
}

int SCC(){
    C = vector<int> (n+1,0);
    for(int i=1;i<=n;i++) if(!C[i]) DFS1(i);
    reverse(order.begin(), order.end());
    int cnt = 0;
    for(int i : order) if(C[i]==-1) DFS2(i, ++cnt);
    return cnt;
}

void dfs(int here){
    visited[here] = true;
    for(int next : DAG[here]){
        if(!visited[next]){
            dfs(next);
        }
    }
}

int main(){
    fast_io;
    int tt; cin >> tt;
    while (tt--) {
        cin >> n >> m;
        for(int i=0;i<m;i++){
            int u, v; cin >> u >> v;
            G[u].push_back(v);
            R[v].push_back(u);
        }
        int SCCcnt = SCC();
        for(int i=1;i<=n;i++){
            for(int next : G[i]){
                if(C[i]==C[next]) continue;
                DAG[C[i]].push_back(C[next]);
            }
        }
        int res = 0;
        visited = vector<bool> (SCCcnt+1, false);
        for(int i=1;i<=SCCcnt;i++){
            if(!visited[i]){
                dfs(i);
                res++;
            }
        }
            
        cout << res << '\n';
        for(int i=0;i<MAX;i++){
            G[i].clear();
            R[i].clear();
            DAG[i].clear();
        }
        order.clear();
    }
}