#include<bits/stdc++.h>

using namespace std;

#define all(x) x.begin(), x.end()
typedef vector <int> vi;
typedef pair<int,int> ii;
typedef long long ll;

const int mod = 1e9 + 7;
const ll inf = 3e18 + 5;

vi adj[100500], path;
bool bio[100500];
ll res;
int I;

void dfs(int S, int u, ll sum, int c){
	if(sum > res){
		res = sum;
		I = S;
	}
	bio[u] = 1;
	for(int v : adj[u]){
		if(bio[v]) continue;
		dfs(S, v, sum + c * v, c + 1);
	}
}

void dfs2(int u, ll sum, int c){
	if(sum == res){
		cout << path.size() << '\n';
		for(int x : path){
			cout << x << '\n';
		}
		exit(0);
	}
	bio[u] = 1;
	for(int v : adj[u]){
		if(bio[v]) continue;
		path.push_back(v);
		dfs2(v, sum + v * c, c + 1);
		path.pop_back();
	}
}

vi cu;

void dfs3(int u, ll sum, int c){
	bio[u] = 1;
	if(sum > res){
		res = sum;
		path = cu;
	}
	for(int v : adj[u]){
		if(bio[v]) continue;
		cu.push_back(v);
		dfs3(v, sum + v * c, c + 1);
		cu.pop_back();
	}
}

int main(){
	ios_base::sync_with_stdio(false);
	cin.tie(0);

    freopen ("maxpath.in", "r", stdin);
    freopen ("maxpath.out", "w", stdout);

	int n, m;
	cin >> n >> m;
	for(int i = 0; i < m; i++){
		int u, v;
		cin >> u >> v;
		adj[u].push_back(v);
		adj[v].push_back(u);
	}
	if(n <= 1000){
		for(int i = 1; i <= n; i++){
			dfs(i, i, i, 2);
			memset(bio, 0, sizeof(bio));
		}
		path.push_back(I);
		dfs2(I, I, 2);
	}
	else{
		for(int i = 1; i <= n; i++){
			if(!bio[i]){
				cu.push_back(i);
				dfs3(i, i, 2);
				cu.pop_back();
			}
		}
		cout << path.size() << '\n';
		for(auto x : path){
			cout << x << '\n';
		}
	}
}