// bzoj1191

#include<algorithm>

#include<iostream>

#include<cstdlib>

#include<cstring>

#include<cstdio>

#include<cmath>

#define LL long long

#define inf 2147483640

#define Pi acos(-1.0)

#define free(a) freopen(a".in","r",stdin),freopen(a".out","w",stdout);

using namespace std;

const int maxn=1010;

struct edge {int to,next;}e[maxn<<2];

int vis[maxn],head[maxn],p[maxn],cnt,n,m;

void link(int u,int v) {

	e[++cnt].to=v;e[cnt].next=head[u];head[u]=cnt;

}

bool find(int x) {

	for (int i=head[x];i;i=e[i].next) if (vis[e[i].to]!=cnt) {

			vis[e[i].to]=cnt;

			if (!p[e[i].to] || find(p[e[i].to])) {

				p[e[i].to]=x;

				return 1;

			}

		}

	return 0;

}

int main() {

	scanf("%d%d",&n,&m);

	for (int u,v,i=1;i<=m;i++) {

		scanf("%d%d",&u,&v);

		link(i,u);link(i,v);

	}

	cnt=0;int ans=0;

	for (int i=1;i<=m;i++) {

		cnt++;

		if (!find(i)) break;

		ans++;

	}

	printf("%d",ans);

	return 0;

}