#include<bits/stdc++.h>
#define N 10002
using namespace std;
int f[5001][5001];
int n,m;
int l;
int match[N],ans;
string str;
int vis[N],temp=1;
void work(){
	int k1=0,k2=0;
	int f1=0;
	for(int i=0;i<str.length();i++){
		if(str[i]!=' '){
			if(f1==0)k1=k1*10+str[i]-'0';
			if(f1==1)k2=k2*10+str[i]-'0';
		}
		else{
			f1=1;
		}
	}
	if(k1){
		f[k1][k2-m]=1;
	}
}
int dfs(int x){
	for(int i=1;i<=m;i++){
		if(f[x][i]&&!vis[i]){
			vis[i]=1;
			if(!match[i]||dfs(match[i])){
				match[i]=x;
				return 1;
			}
		}
	}
	return 0;
}
int main(){
	freopen("tongzhuo.in","r",stdin);
	freopen("tongzhuo.out","w",stdout);
	cin>>l>>m;
	n=l-m;
	while(getline(cin,str)){
		work();
	}
	for(int i=1;i<=n;i++){
		ans+=dfs(i);
		memset(vis,0,sizeof(vis));
	}
	cout<<ans;
	
	//cout<<endl;
	//for(int i=1;i<=m;i++)cout<<i<<":"<<match[i]<<endl;
	
}