#include<algorithm>
#include<iostream>
#include<random>
#include<vector>
#include<cstdio>
using namespace std;
#define For(i,l,r) for(int i=l;i<=r;i++)
#define FOR(i,l,r) for(int i=l;i>=r;i--)
#define MAXN 20001
int N,M,tot,dfn[MAXN],low[MAXN];vector<int>E[MAXN];bool ans[MAXN];
int get(){int x=0,f=1;char c=getchar();while(c<'0'||c>'9')c=='-'&&(f=-1),c=getchar();while(c>='0'&&c<='9')x=x*10+c-'0',c=getchar();return x*f;}
void dfs(int u,bool isrt){dfn[u]=low[u]=++tot;int c=0;for(auto v:E[u]){if(!dfn[v]){dfs(v,0),low[u]=min(low[u],low[v]),c++;if(!isrt&&low[v]>=dfn[u])ans[u]=1;}low[u]=min(low[u],low[v]);}if(isrt&&c>1)ans[u]=1;}
int main()
{
	N=get(),M=get();For(i,1,M){int u=get(),v=get();E[u].push_back(v),E[v].push_back(u);}
	For(i,1,N)if(!dfn[i])dfs(i,1);int c=0;For(i,1,N)c+=ans[i];cout<<c<<'\n';For(i,1,N)if(ans[i])cout<<i<<' ';cout<<'\n';return 0;
}