#include<stdio.h>
#include<string.h>
#include<stack>
#include<queue>
#include<vector>
#include<algorithm>
#define MAX 5200
#define MAXM 200100
using namespace std;
vector<int>newmap[MAX];
vector<int>scc[MAX];
int sccno[MAX];
int in[MAX],out[MAX];
int scccnt,dfsclock;
int n,m;
int low[MAX],dfn[MAX];
int instack[MAX];
int ans,head[MAX];
int vis[MAX],city[MAX];
stack<int>s;
struct node
{
	int beg,end,next;
}edge[MAXM];
void init()
{
	ans=0;
	memset(head,-1,sizeof(head));
}
void add(int u,int v)
{
	edge[ans].beg=u;
	edge[ans].end=v;
	edge[ans].next=head[u];
	head[u]=ans++;
}
void getmap()
{
	int a,b;
	while(m--)
	{
		scanf("%d%d",&a,&b);
		add(a,b);
	}
}
void tarjan(int u)
{
	int v,i,j;
	low[u]=dfn[u]=++dfsclock;
	s.push(u);
	instack[u]=1;
	for(i=head[u];i!=-1;i=edge[i].next)
	{
		v=edge[i].end;
		if(!dfn[v])
		{
			tarjan(v);
			low[u]=min(low[u],low[v]);
		}
		else if(instack[v])
		    low[u]=min(low[u],dfn[v]);
    }
    if(dfn[u]==low[u])
    {
    	scccnt++;
    	while(1)
    	{
    		v=s.top();
    		s.pop();
    		instack[v]=0;
    		sccno[v]=scccnt;
    		if(v==u)
    		    break;
    	}
    }
}
void find(int l,int r)
{
	memset(low,0,sizeof(low));
	memset(dfn,0,sizeof(dfn));
	memset(instack,0,sizeof(instack));
	memset(sccno,0,sizeof(sccno));
	dfsclock=scccnt=0;
	for(int i=l;i<=r;i++)
	{
		if(!dfn[i])
		    tarjan(i);
	}
}
void suodian()
{
	find(1,n);
	for(int i=1;i<=scccnt;i++)
		newmap[i].clear();
	memset(in,0,sizeof(in));
	memset(out,0,sizeof(out));
	int u,v,i,j;
	for(i=0;i<ans;i++)
	{
		u=sccno[edge[i].beg];
		v=sccno[edge[i].end];
		if(u!=v)
		{
			newmap[u].push_back(v);
			in[v]++;
			out[u]++;
		}		
	}
}
int query(int x)
{
	int i,j;
	for(i=0;i<newmap[x].size();i++)
	{
		int y=newmap[x][i];
		if(!vis[y])
		{
			vis[y]=1;
			if(city[y]==0||query(city[y]))
			{
				city[y]=x;
				return 1;
			}
		}
	}
	return 0;
}
void solve()
{
	int i,j;
	int sum=0;
	memset(city,0,sizeof(city));
	for(i=1;i<=scccnt;i++)
	{
		memset(vis,0,sizeof(vis));
		if(query(i))
		   sum++;
	}
	printf("%d\n",scccnt-sum);//最小路径覆盖=顶点数-最大匹配数 
}
int main()
{
	int t;
	scanf("%d",&t);
	while(t--)
	{
		scanf("%d%d",&n,&m);
		init();
		getmap();
		suodian();
		solve();
	}
	return 0;
}