1 #include<iostream>
 2 #include<cstdio>
 3 #include<cstring>
 4 using namespace std;
 5 int match[501],n,m,a,b,ans=0;
 6 bool used[501],map[501][501];
 7 bool check(int u){
 8     for(int i=1;i<=m;i++){
 9         if(map[u][i]&&!used[i]){
10             used[i]=true;
11             if(!match[i]||check(match[i])){
12                 match[i]=u;
13                 return true;
14             }
15         }
16     }
17     return false;
18 }
19 int main(){
20     memset(map,0,sizeof(map));
21     memset(match,0,sizeof(match));
22     scanf("%d%d",&n,&m);
23     for(int i=1;i<=m;i++){
24         scanf("%d%d",&a,&b);
25         map[a][b]=true;
26     }
27     for(int i=1;i<=n;i++){
28         memset(used,0,sizeof(used));
29         if(check(i))ans++;
30     }
31     printf("%d",ans);
32 }