#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
#define faster ios_base::sync_with_stdio(false);cin.tie(NULL); cout.tie(NULL);
int n, m;
const int N = 1005;
vector<int> adj[N];
bool visited[N];
vector<int> largest_component;

void inp() {
    cin >> n >> m;
    for(int i = 1; i <= m; i++) {
        int x, y; cin >> x >> y;
        adj[x].push_back(y);
        adj[y].push_back(x);
    }
}

int dfs(int u, vector<int> &component) {
    int cnt = 1;
    component.push_back(u);
    visited[u] = true;
    for(auto v : adj[u]) {
        if(!visited[v]) {
            cnt += dfs(v, component);
        }
    }
    return cnt;
}

void ntkt() {
    memset(visited, false, sizeof(visited));
    int max_size = 0;

    for(int i = 1; i <= n; i++) {
        if(!visited[i]) {
            vector<int> tmp_path;
            int size = dfs(i, tmp_path);
            if(size > max_size) {
                max_size = size;
                largest_component = tmp_path;
            }
        }
    }

    cout << max_size << "\n";
    for(auto x : largest_component) cout << x << " ";
    cout << "\n";
}

int main() {
    faster;
    inp();
    ntkt();
    return 0;
}