#include<iostream>
#include<cstdio>
#pragma comment(linker, "/STACK:1024000000,1024000000")
#include<iostream>
#include<cstdio>
#include<cmath>
#include<string>
#include<queue>
#include<algorithm>
#include<stack>
#include<cstring>
#include<vector>
#include<list>
#include<set>
#include<map>
#include<bitset>
using namespace std;
#define LL unsigned long long
#define pi (4*atan(1.0))
#define eps 1e-4
#define bug(x)  cout<<"bug"<<x<<endl;
const int N=5e3+10,M=1e5+10,inf=1e9+10;
const LL INF=1e18+10,mod=2147493647;

struct is
{
    int u,v;
    int next;
}edge[M];
int head[N];
int belong[N];
int dfn[N];
int low[N];
int stackk[N<<1];
int instack[N];
int number[N];
int n,m,jiedge,lu,bel,top;
void update(int u,int v)
{
    jiedge++;
    edge[jiedge].u=u;
    edge[jiedge].v=v;
    edge[jiedge].next=head[u];
    head[u]=jiedge;
}
void dfs(int x)
{
    dfn[x]=low[x]=++lu;
    stackk[++top]=x;
    instack[x]=1;
    for(int i=head[x];i;i=edge[i].next)
    {
        if(!dfn[edge[i].v])
        {
            dfs(edge[i].v);
            low[x]=min(low[x],low[edge[i].v]);
        }
        else if(instack[edge[i].v])
        low[x]=min(low[x],dfn[edge[i].v]);
    }
    if(low[x]==dfn[x])
    {
        int sum=0;
        bel++;
        int ne;
        do
        {
            sum++;
            ne=stackk[top--];
            belong[ne]=bel;
            instack[ne]=0;
        }while(x!=ne);
        number[bel]=sum;
    }
}
void tarjan()
{
    memset(dfn,0,sizeof(dfn));
    bel=lu=top=0;
    for(int i=1;i<=n;i++)
    if(!dfn[i])
    dfs(i);
}
void init()
{
    memset(head,0,sizeof(head));
    jiedge=0;
}
vector<int> g[N];
int cy[N];
bool vis[N];
bool dfs1(int u){
    for(int i=0; i<g[u].size(); ++i){
        int v = g[u][i];
        if(vis[v]) continue;
        vis[v] = true;
        if(cy[v]==-1 || dfs1(cy[v])){
            cy[v] = u;
            return true;
        }
    }
    return false;
}
int solve(int n){
    int ret = 0;
    memset(cy, -1, sizeof(cy));
    for(int i=1;i<=n;++i){
        memset(vis, 0, sizeof(vis));
        ret += dfs1(i);
    }
    return n - ret;
}


int main()
{
    int T;
    scanf("%d",&T);
    while(T--)
    {
        init();
        scanf("%d%d",&n,&m);
        for(int i=1;i<=n;i++)
            g[i].clear();
        for(int i=1;i<=m;i++)
        {
            int u,v;
            scanf("%d%d",&u,&v);
            update(u,v);
        }
        tarjan();
        for(int i=1;i<=jiedge;i++)
        {
            if(belong[edge[i].v]!=belong[edge[i].u])
            {
                g[belong[edge[i].u]].push_back(belong[edge[i].v]);
            }
        }
        int ans=solve(bel);
        printf("%d\n",ans);
    }
    return 0;
}