#include <bits/stdc++.h>
using namespace std;
 
bool mapp[10005][10005];
int A[10005];
int m,n;
bool vis[10005];
int ans;
 
bool dfs(int x){
	for(int i=m+1;i<=n;i++){
		if(mapp[x][i] && !vis[i]){
			vis[i]=1;
			if(!A[i] || dfs(A[i]) ){
				A[i]=x;
				return 1;
			}
		}
	}
	return 0;
}
 
int main(){
	freopen("tongzhuo.in","r",stdin);
	freopen("tongzhuo.out","w",stdout);
	cin >> n >> m;
	int a,b;
	while(scanf("%d %d",&a,&b) == 2){
		mapp[a][b]=1;
	}
	for(int i=1;i<=m;i++){
		memset(vis,0,sizeof(vis));
		if(dfs(i)){
			ans++;
		}
	}
	cout << ans;
	return 0;
}