RT，样例都没过。

#include<bits/stdc++.h>
#define ll long long
using namespace std;
const int N=20005;
ll n,m,tot;
vector<ll>e[N];
priority_queue<ll,vector<ll>,greater<ll> > q;//对答案排序
ll dfn[N],low[N];
void dfs(int u,int fa){//tarjan
	dfn[u]=low[u]=++tot;
    int count=0;
	for(int i=0;i<e[u].size();i++){
		int v=e[u][i];
		if(dfn[v]&&v!=fa)low[u]=min(low[u],dfn[v]);
		else if(!dfn[v]){
			dfs(v,u);
			low[u]=min(low[u],low[v]);
			if(low[v]>=dfn[u]){
                count++;
                if(u!=fa||count>1)q.push(u);
            }
		}
	}
}
int main(){
	scanf("%lld%lld",&n,&m);
	for(int i=1;i<=m;i++){
		ll u,v;scanf("%lld%lld",&u,&v);
		e[u].push_back(v);
		e[v].push_back(u);
	}
	for(int i=1;i<=n;i++)if(!dfn[i])dfs(i,i);
    //for(int i=1;i<=n;i++)cout<<dfn[i]<<' '<<low[i]<<endl;
	while(!q.empty()){
		ll u=q.top();
		printf("%lld\n",u);
		q.pop();
	}
	return 0;
}