#include <bits/stdc++.h>
using namespace std;
const int MAXN = 20005;
const int MAXM = 100005;
int n, m, fir[MAXN], nxt[MAXM<<1], to[MAXM<<1], cnt=1;
int dfn[MAXN], low[MAXN], tot;
int cur, Ans[MAXN];
bool is_bridge[MAXM<<1];
void tarjan(int u, int ff)
{
dfn[u] = low[u] = ++tot;
int out = 0; bool flag = 0;
for(int i = fir[u]; i; i = nxt[i])
if(!dfn[to[i]])
{
out++, tarjan(to[i], i), low[u] = min(low[u], low[to[i]]);
if(dfn[u] <= low[to[i]]) flag = 1; //存割点
if(dfn[u] < low[to[i]]) is_bridge[i] = 1; //存桥
}
else if((i^1) != ff) low[u] = min(low[u], dfn[to[i]]);
if(!ff && out == 1) flag = 0;
if(flag) Ans[++cur] = u;
}
void Add(int u, int v) { to[++cnt] = v; nxt[cnt] = fir[u]; fir[u] = cnt; }
int main ()
{
int x, y;
scanf("%d%d", &n, &m);
for(int i = 1; i <= m; i++)
scanf("%d%d", &x, &y), Add(x, y), Add(y, x);
for(int i = 1; i <= n; i++)
if(!dfn[i]) tarjan(i, 0);
printf("%d
", cur);
sort(Ans + 1, Ans + cur + 1);
for(int i = 1; i <= cur; i++) // 输出割点
printf("%d%c", Ans[i], i == n ? '
' : ' ');
}