#include <bits/stdc++.h>
using namespace std;
const int N=10000+5;
int n,m;
bool mp[N][N]={0};
int match[N]={0};
int ans=0;
bool vis[N]={0};
int change(int pt){
    for (int i=m+1;i<=n;i++){
        if (mp[pt][i]==1&&vis[i]==0){
            vis[i]=1;
            if (match[i]==0||change(match[i])==0){
                match[i]=pt;
                return 0;
            }
        }
    }
    return 1;
}
void hun(){
    for (int i=1;i<=m;i++){
        memset(vis,0,sizeof(vis));
        if (change(i)==0)ans++;
    }
    return ;
}
int main(){
    freopen ("tongzhuo.in","r",stdin);
    freopen ("tongzhuo.out","w",stdout);
    scanf("%d%d",&n,&m);
    int a,b;
    while(scanf("%d%d",&a,&b)!=EOF){
        mp[a][b]=1;
    }
    hun();
    cout<<ans<<endl;
    return 0;
}