#include<cstdio>

#include<algorithm>

#include<cstring>

using namespace std;

const int maxn=1e6+;

int father[maxn],isRoot[maxn],T,M,N,u,v,visit[maxn];

void init () {

    for (int i=;i<maxn;i++) father[i]=i;

    fill (isRoot,isRoot+maxn,);

    fill (visit,visit+maxn,);

}

int findfather (int x) {

    int a=x;

    while (x!=father[x]) x=father[x];

    while (a!=father[a]) {

        int z=a;

        a=father[a];

        father[z]=x;

    }

    return x;

}

void Union (int a,int b) {

    int faA=findfather(a);

    int faB=findfather(b);

    if (faA!=faB) father[faA]=faB;

}

int main () {

    while (~scanf ("%d",&T)) {

        while (T--) {

            init ();

            scanf ("%d %d",&N,&M);

            for (int i=;i<M;i++) {

                scanf ("%d %d",&u,&v);

                visit[v]=;

                Union (u,v);

            }

            for (int i=;i<=N;i++) isRoot[findfather(i)]++;

            int ans=,ans1=;

            for (int i=;i<=N;i++) if (isRoot[i]) ans++;

            for (int i=;i<=N;i++) if (!visit[i]) ans1++;

            printf ("%d\n",max(ans,ans1));

        }

    }

    return ;

}