#include<iostream>#include<cstdio>#include<cstdlib>#include<cstring>#include<algorithm>using namespace std;const int N=505*2,M=N*N+10;int next[M],head[N],list[M],tot,n,m;void add(int a,int b){tot++;list[tot]=b;next[tot]=head[a];head[a]=tot;}int fa[N],vis[N];bool dfs(int v){for(int i=head[v];i;i=next[i]){int u=list[i];if(!vis[u]){vis[u]=1;if(fa[u]==0||dfs(fa[u])){fa[u]=v;return 1;}}}return 0;}int main(){while(scanf("%d%d",&n,&m)!=EOF){memset(head,0,sizeof head);tot=0;memset(fa,0,sizeof fa);for(int i=1;i<=m;i++){int a,b;scanf("%d%d",&a,&b);add(a,b);}int ans=0;for(int i=1;i<=n;i++){memset(vis,0,sizeof vis);ans+=dfs(i);}printf("%dn",ans);} return 0;}
