#include<bits/stdc++.h>
using namespace std;
typedef long long ll;
#define N 10005
#define M 4000005
int n,m,x,y,head[N],tot=1,cur[N],dep[N],s,t,maxflow;
bool vis[N];
struct node{
	int to,next,w;
	node (int to=0,int next=0,int w=0)
		:to(to),next(next),w(w){}
}e[M];
ll read(){
	ll w=0,f=1;
	char ch=getchar();
	while (ch>'9'||ch<'0'){
		if (ch=='-') f=-1;
		ch=getchar();
	}
	while (ch>='0'&&ch<='9'){
		w=(w<<3)+(w<<1)+(ch^48);
		ch=getchar();
	}
	return w*f;
}
void adde(int u,int v,int w){
	e[++tot]=node(v,head[u],w);
	head[u]=tot;
}
bool bfs(){
	for (int i=1;i<=n+2;i++) cur[i]=head[i],vis[i]=0,dep[i]=1<<30;
	dep[s]=0;
	queue<int> q;
	q.push(s);
	while (!q.empty()){
		int u=q.front();
		q.pop();
		vis[u]=0;
		for (int i=head[u];i;i=e[i].next){
			int v=e[i].to;
			if (dep[v]>dep[u]+1&&e[i].w){
				dep[v]=dep[u]+1;
				if (!vis[v]){
					q.push(v);
					vis[v]=1;
				}
			}
		}
	}
	if (dep[t]!=1<<30) return 1;
	return 0;
}
int dfs(int u,int flow){
	ll rlow=0;
	if (u==t){
		maxflow+=flow;
		return flow;
	}
	int used=0;
	for (int i=cur[u];i;i=e[i].next){
		cur[u]=i;
		int v=e[i].to;
		if (e[i].w&&dep[v]==dep[u]+1){
			if (rlow=dfs(v,min(flow-used,e[i].w))){
				used+=rlow;
				e[i].w-=rlow;
				e[i^1].w+=rlow;
				if (used==flow) break;
			}
		}
	}
	return used;
}
int dinic(){
	while (bfs()){
		dfs(s,1<<30);
	}
	return maxflow;
}
int main(){
	freopen("tongzhuo.in","r",stdin);
	freopen("tongzhuo.out","w",stdout);
	n=read(),m=read();
	s=n+1,t=n+2; 
	for (int i=1;i<=m;i++) adde(n+1,i,1),adde(i,n+1,0);
	for (int i=m+1;i<=n;i++) adde(i,n+2,1),adde(n+2,i,0);
	while (scanf("%d %d",&x,&y)==2){
		adde(x,y,1),adde(y,x,0);
	}
	printf("%d\n",dinic());
	return 0;
}