#include<bits/stdc++.h>

#define maxn 105

using namespace std;

int n,n1,n2,ans=;

vector<int> v[maxn];

int vis[maxn],tim,hav[maxn];

bool Dfs(int rt){

    for(int i=;i<v[rt].size();i++){

        int to=v[rt][i];

        if(vis[to]!=tim){

            vis[to]=tim;

            if(!hav[to]||Dfs(hav[to])){

                hav[to]=rt;

                return true;

            }

        }

    }

    return false;

}

int main(){

//    freopen("flyer.in","r",stdin);

//    freopen("flyer.out","w",stdout);

    scanf("%d%d",&n,&n1);int n2=n-n1;

    int x,y;

    while(scanf("%d%d",&x,&y)!=EOF) v[x].push_back(y);

    for(int i=;i<=n1;i++)

        tim++,ans+=Dfs(i);

    printf("%d",ans);

    return ;

}