#include<iostream>
#include<algorithm>
#include<cstdio>
#include<cstring>
using namespace std;
int n,m;
int cnt=2;
int alist[6000001];
struct data{
    int v;int next;int value;
}edge[6000001];
void add(int u,int v,int value){
    edge[cnt].v=v;
    edge[cnt].value=value;
    edge[cnt].next=alist[u];
    alist[u]=cnt++;
    return ;
}
int h[1000001];
int q[1000001];
bool bfs(){
    int x,next;
    memset(h,-1,sizeof(h));
    int head=0,tail=1;
    q[head]=1;
    h[1]=0;
    while(head<tail){
        x=q[head++];
        next=alist[x];
        while(next){
            int v=edge[next].v;
            int value=edge[next].value;
            if(value&&h[v]<0){
                q[tail++]=v;
                h[v]=h[x]+1;
            }
            next=edge[next].next;
        }
    }
    if(h[n]==-1) return false;
    return true;
}
int ans;
int dfs(int x,int y){
    if(x==n) return y;
    int next=alist[x];
    int w,used=0;
    while(next){
        int v=edge[next].v;
        int value=edge[next].value;
        if(value&&h[v]==h[x]+1){
                w=y-used;
                w=dfs(v,min(w,value));
                edge[next].value-=w;
                edge[next^1].value+=w;
                used+=w;
                if(used==y) return y;
        }
        next=edge[next].next;
    }
    if(!used) h[x]=-1;
    return used;
}
void dinic(){
    while(bfs()) ans+=dfs(1,0x7fffffff);
}
int n1,m1;
int main(){
    freopen("tongzhuo.in","r",stdin);
    freopen("tongzhuo.out","w",stdout);
    cin>>n1>>m1;n1-=m1;swap(n1,m1);
    n=n1+m1+2;
    for(int i=1;i<=n1;i++){
        add(1,i+1,1);
        add(i+1,1,1);
    }
    int u,v;
    while(cin>>u>>v){
        add(u+1,v+1,1),add(v+1,u+1,1);
    }
    for(int i=1;i<=m1;i++){
        add(i+1,n,1);
        add(n,i+1,1);
    }
    dinic();cout<<ans<<endl;
    return 0;
}