hdu1151

#include<cstdio>
#include<cmath>
#include<algorithm>
#include<cstring>
using namespace std;
const int N=505;
int fi[N],num,T,n,m,ne[N*N],zz[N*N],f[N],match[N],x,y;
void jb(int x,int y)
{
    ne[++num]=fi[x];
    fi[x]=num;
    zz[num]=y;
}
int dfs(int x)
{
    for (int i=fi[x];i;i=ne[i])
     if (!f[zz[i]])
      {
          f[zz[i]]=1;
          if (!match[zz[i]]||dfs(match[zz[i]]))
           {
               match[zz[i]]=x;
               return 1;
           }
      }
    return 0;  
}
int main()
{
    scanf("%d",&T);
    while (T--)
     {
         memset(match,0,sizeof match);
         memset(fi,0,sizeof fi);
         num=0;
         scanf("%d%d",&n,&m);
         while (m--)
          {
              scanf("%d%d",&x,&y);
              jb(x,y);
          }
         int ans=0;
        for (int i=1;i<=n;i++)
         {
             memset(f,0,sizeof f);
             ans+=dfs(i);
         } 
        printf("%d\n",n-ans); 
     } 
}