#include <iostream>
#include <cstring>
#include <cmath>
#include <algorithm>
#include <vector>
#include <queue>
#include <cstdio>
using namespace std;
const int maxn = 205;
const int INF = 1e9+10;
const double eps = 1e-8;
struct Edge{
    int to, rev;
    double cap;
    Edge(int _to, double _cap, int _rev):to(_to), cap(_cap), rev(_rev){}
};
vector<Edge> G[maxn];
int cnt[maxn];
int level[maxn];
int s, t;
int n, m;
int d[maxn];
void add_edge(int u, int v, double cap){
    G[u].push_back(Edge(v, cap, G[v].size()));
    G[v].push_back(Edge(u, 0, G[u].size()-1));
}
void bfs(int s){
    memset(level, -1, sizeof(level));
    queue<int> q;
    q.push(s);
    level[s] = 0;
    while(!q.empty()){
        int v = q.front();
        q.pop();
        for(int i=0; i<G[v].size(); i++){
            Edge& e = G[v][i];
            if(e.cap>eps&&level[e.to]<0){
                level[e.to] = level[v]+1;
                q.push(e.to);
            }
        }
    }
}
double dfs(int v, int t, double flow){
    if(v == t) return flow;
    for(int& i=cnt[v]; i<G[v].size(); i++){
        Edge& e = G[v][i];
        if(e.cap>0&&level[v]<level[e.to]){
            double d = dfs(e.to, t, min(flow, e.cap));
            if(d>eps){
                e.cap -= d;
                G[e.to][e.rev].cap += d;
                return d;//一旦有一条路径满足就立即返回！
            }
        }
    }
    return 0;
}
double max_flow(int s, int t){
    double flow = 0;
    for(;;){
        //构造层次图
        bfs(s);
        //无法连通终点，结束访问
        if(level[t]<0) return flow;
        double f;
        //cnt数组记录在递归的过程中的边的顺序。
        memset(cnt, 0, sizeof(cnt));
        //当存在增广路的时候不断的进行增广
        while((f = dfs(s, t, INF))>eps){
            //cout<<"qiu "<<f<<endl;
            flow+=f;
        }
    }
}
int x[1024], y[1024];
void graph(double g){
    for(int i=0; i<=n+1; i++){
        G[i].clear();
    }
    for(int i=0; i<m; i++){
        add_edge(x[i], y[i], 1.0), add_edge(y[i], x[i], 1.0);
    }
    for (int i = 1; i <= n; i++)
	{
		add_edge(s, i, m);
		add_edge(i, t, m + 2 * g - d[i]);
	}
}
int sum = 0;
bool vis[maxn];
void dfs_ans(int u){
    sum++;
    vis[u] = true;
    for(int i=0; i<G[u].size(); i++){
        Edge v = G[u][i];
        if(v.cap>eps&&!vis[v.to]){
            dfs_ans(v.to);
        }
    }
}
int main()
{
    while(~scanf("%d%d", &n, &m)){
        if(m == 0){
            printf("1\n1\n");
            continue;
        }
        for(int i=0; i<maxn; i++) d[i] = 0;
        int u, v;
        for(int i=0; i<m; i++){
            scanf("%d%d", &x[i], &y[i]);
            d[x[i]]++, d[y[i]]++;
        }
        s = 0;
        t = n+1;
        double l=0, r=m;
        double mid;
        const double presion = 1.0/n/n;
        while(r-l>=presion){
            mid = ((l+r)/2.0);
            //cout<<l<<" "<<r<<" "<<mid<<endl;
            graph(mid);
            //未满流
            //cout<<"out"<<endl;
            if((n*m-max_flow(s, t))/2.0>eps) l=mid;
            else r=mid;
        }
        graph(l);
        max_flow(s, t);
        sum = 0, memset(vis, 0, sizeof(vis));
        dfs_ans(0);
        printf("%d\n", sum-1);
        for(int i=1; i<=n; i++) {
            if(vis[i]) printf("%d\n", i);
        }
    }
    return 0;
}