#include<bits/stdc++.h>
#include<iostream>
#include<cstring>
#include<cstdio>
using namespace std;
//input by bxd
#define rep(i,a,b) for(int i=(a);i<=(b);i++)
#define repp(i,a,b) for(int i=(a);i>=(b);--i)
#define RI(n) scanf("%d",&(n))
#define RII(n,m) scanf("%d%d",&n,&m)
#define RIII(n,m,k) scanf("%d%d%d",&n,&m,&k)
#define RS(s) scanf("%s",s);
#define ll long long
#define pb push_back
#define REP(i,N)  for(int i=0;i<(N);i++)
#define CLR(A,v)  memset(A,v,sizeof A)
//
#define inf 0x3f3f3f3f
const int N=5000+5;
int head[20*N],pos;
struct Edge
{int to,nex;
}edge[20*N];
void add(int a,int b)
{edge[++pos].nex=head[a];head[a]=pos;edge[pos].to=b;
}
int low[N],dfn[N],inde,Stack[N],vis[N],tot,cnt,belong[N],out[N];vector<int>G[N];
int used[N];
void init()
{CLR(dfn,0);CLR(vis,0);CLR(low,0);CLR(out,0);pos=inde=tot=cnt=0;CLR(head,0);}
void tarjan(int x)
{dfn[x]=low[x]=++tot;Stack[++inde]=x;vis[x]=1;for(int i=head[x];i;i=edge[i].nex){int v=edge[i].to;if(!dfn[v]){tarjan(v);low[x]=min(low[x],low[v]);}else if(vis[v])low[x]=min(low[x],low[v]);}if(dfn[x]==low[x]){cnt++;int v;do{v=Stack[inde--];vis[v]=0;belong[v]=cnt;}while(v!=x);}
}bool dfs(int x)
{if(G[x].size())rep(j,0,G[x].size()-1){int t=G[x][j];if(!used[t]){used[t]=1;if(!vis[t]||dfs(vis[t])){vis[t]=x;return true;}}}return false;
}int find1(void )
{int ans=0;CLR(vis,0);rep(i,1,cnt){CLR(used,0);if(dfs(i))ans++;}return ans;
}int main()
{int cas;RI(cas);while(cas--){int n,m;RII(n,m);rep(i,1,m){int a,b;RII(a,b);add(a,b);}rep(i,1,n)if(!dfn[i])tarjan(i);rep(i,1,n){int u=belong[i];for(int j=head[i];j;j=edge[j].nex){int v=belong[ edge[j].to ];if(u!=v)G[u].pb(v);}}cout<<cnt-find1()<<endl;rep(i,1,cnt)G[i].clear();init();}return 0;
}