1 #include <cstdio>
2 #include <cstring>
3 #include <cstdlib>
4 #include <algorithm>
5 using namespace std;
6
7 #define MAXN 150
8 int n; //十字路口的数量
9 int m; //路的个数
10 int map[MAXN][MAXN];
11 int x[MAXN], y[MAXN];
12 int mark[MAXN];
13
14 int search(int a)
15 {
16 for (int i = 1; i <= n; i++)
17 {
18 if (map[a][i] && !mark[i])
19 {
20 mark[i] = 1;
21 if (y[i] == 0 || search(y[i]))
22 {
23 x[a] = i;
24 y[i] = a;
25 return a;
26 }
27 }
28 }
29 return 0;
30 }
31
32 int main()
33 {
34 int t;
35 scanf("%d", &t);
36 while (t--)
37 {
38 memset(map, 0, sizeof(map));
39 memset(mark, 0, sizeof(mark));
40 scanf("%d %d", &n, &m);
41 for (int i = 0; i < m; i++)
42 {
43 int a, b;
44 scanf("%d %d", &a, &b);
45 if (map[a][b] == 0)
46 map[a][b] = 1;
47 }
48
49 int ans1 = 0;
50 memset(x, 0, sizeof(x));
51 memset(y, 0, sizeof(y));
52
53 for (int i = 1; i <= n; i++)
54 {
55 if (x[i] == 0)
56 {
57 memset(mark, 0, sizeof(mark));
58 if (search(i))
59 ans1++;
60 }
61 }
62 printf("%d\n", n - ans1);
63 }
64 //system("pause");
65 return 0;
66 }
