1 #include<iostream>
 2 #include<stdio.h>
 3 #include<string.h>
 4 #include<algorithm>
 5 using namespace std;
 6 int mmap[555][555];//存图
 7 int vis[555];
 8 int match[555];//匹配过
 9 int n;//总点数
10 bool dfs(int u)
11 {
12     for (int v = 1; v <= n; v++)
13     {
14         if (mmap[u][v] && !vis[v])
15         {
16             vis[v] = true;
17             if (match[v] == -1 || dfs(match[v]))
18             {
19                 match[v] = u;
20                 return true;
21             }
22         }
23     }
24     return false;
25 }
26 int main()
27 {
28     memset(mmap, 0, sizeof(mmap));
29     int k;//边数
30     scanf("%d%d", &n, &k);//n个点k个边
31     int i, a, b;
32     for (i = 0; i<k; i++)
33     {
34         scanf("%d%d", &a, &b);
35         mmap[a][b] = 1;//连边a->b 要单向边
36     }
37     int sum = 0;//匹配数
38     memset(match, -1, sizeof(match));//初始化为-1
39     for (int i = 1; i <= n; i++)
40     {
41         memset(vis, 0, sizeof(vis));
42         if (dfs(i))//是否有增广路，有的话匹配数+1
43             sum++;
44     }
45     printf("%d\n", sum);
46 }