Description：

Solution：

Code：

#include<algorithm>

#include<iostream>

#include<cstdlib>

#include<cstdio>

#include<cmath>

#include<stack>

#include<vector>

#include<cctype>

#include<cstring>

using namespace std;

int n,m;

#define MAXN 100010

struct edge

{

	int to,nxt;

}e[MAXN << 1];

int edgenum = 0;

int lin[MAXN] = {0};

int deg[MAXN];

void add(int a,int b)

{

	++deg[a];++deg[b];

	++edgenum;e[edgenum].to = b;e[edgenum].nxt = lin[a];lin[a] = edgenum;

	++edgenum;e[edgenum].to = a;e[edgenum].nxt = lin[b];lin[b] = edgenum;

	return;

}

int dfn[MAXN],low[MAXN],tot = 0;

stack<int> s;

int root;

bool cut[MAXN];

void tarjan(int k)

{

	dfn[k] = low[k] = ++tot;

	s.push(k);

	int flag = 0;

	for(int i = lin[k];i != 0;i = e[i].nxt)

	{

		if(dfn[e[i].to] == 0)

		{

			tarjan(e[i].to);

			low[k] = min(low[k],low[e[i].to]);

			if(low[e[i].to] >= dfn[k])

			{

				++flag;

				if(k != root || flag > 1)cut[k] = true;

			}

		}

		else

		{

			low[k] = min(low[k],dfn[e[i].to]);

		}

	}

	return;

}

int ans = 0;

vector<int> res;

int main()

{

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

	int a,b;

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

	{

		scanf("%d%d",&a,&b);

		add(a,b);

	}

	for(int i = 1;i <= n;++i)

	{

		if(dfn[i] == 0)

		{

			root = i;

			tarjan(i);

		}

	}

	for(int i = 1;i <= n;++i)

	{

		if(!cut[i] && deg[i] == m - (n - 2))

		{

			++ans;

			res.push_back(i);

		}

	}

	cout << ans << endl;

	for(int i = 0;i < res.size();++i)

	{

		printf("%d ",res[i]);

	}

	cout << endl;

	return 0;

}