#include <iostream>
#include <cstring>
using namespace std;
const int N = 20005, M = 100005;
int n, m, eid, p[N];
int dfn[N], low[N];
bool iscut[N];
int cnt;
struct edge {
	int v, next;
} E[M * 2];
void insert(int u, int v) {
	E[eid].v = v;
	E[eid].next = p[u];
	p[u] = eid++;
}
int times;
void dfs(int u, int fa) {
	dfn[u] = low[u] = ++times;
	int child = 0;
	for (int i = p[u]; i != -1; i = E[i].next) {
		int v = E[i].v;
		if (dfn[v] == 0) {
			dfs(v, u);
			++child;
			low[u] = min(low[u], low[v]);
			if (low[v] >= dfn[u]) {
				iscut[u] = true;
				cnt++;
			}
		} else if (dfn[v] < dfn[u] && v != fa) {
			low[u] = min(low[u], dfn[v]);
		}
	}
	if (fa < 0 && child == 1) {
		iscut[u] = false;
		cnt--;
	}
} 
int main() {
	cin >> n >> m;
	memset(p, -1, sizeof(p));
	for (int i = 1; i <= m; i++) {
		int u, v;
		cin >> u >> v;
		insert(u, v);
		insert(v, u);
	}
	for (int i = 1; i <= n; i++) {
		if (dfn[i] == 0) {
			dfs(i, -1);
		}
	}
	cout << cnt << endl;
	for (int i = 1; i <= n; i++) {
		if (iscut[i] == true) {
			cout << i << ' ';
		}
	}
	return 0;
}

下面有个讨论说，计数时不要在函数里面计 那样写交上只有44分(・∀・(・∀・(・∀・*)