#include <cstdio>

 #include <cstring>

 #include <cstdlib>

 #include <algorithm>

 using namespace std;

 #define MAXN 150

 int n;    //十字路口的数量

 int m;    //路的个数

 int map[MAXN][MAXN];

 int x[MAXN], y[MAXN];

 int mark[MAXN];

 int search(int a)

 {

     for (int i = ; i <= n; i++)

     {

         if (map[a][i] && !mark[i])

         {

             mark[i] = ;

             if (y[i] ==  || search(y[i]))

             {

                 x[a] = i;

                 y[i] = a;

                 return a;

             }

         }

     }

     return ;

 }

 int main()

 {

     int t;

     scanf("%d", &t);

     while (t--)

     {

         memset(map, , sizeof(map));

         memset(mark, , sizeof(mark));

         scanf("%d %d", &n, &m);

         for (int i = ; i < m; i++)

         {

             int a, b;

             scanf("%d %d", &a, &b);

             if (map[a][b] == )

                 map[a][b] = ;

         }

         int ans1 = ;

         memset(x, , sizeof(x));

         memset(y, , sizeof(y));

         for (int i = ; i <= n; i++)

         {

             if (x[i] == )

             {

                 memset(mark, , sizeof(mark));

                 if (search(i))

                     ans1++;

             }

         }

         printf("%d\n", n - ans1);

     }

     //system("pause");

     return ;

 }