#include "bits/stdc++.h"
using namespace std;
#define pb push_back
#define endl "\n"
#define int long long
#define sz(x) ((int)(x).size())
#define all(x) (x).begin(),(x).end()
/* stuff you should look for
* int overflow, array bounds
* special cases (n=1?)
* do smth instead of nothing and stay organized
* WRITE STUFF DOWN
* DON'T GET STUCK ON ONE APPROACH
* SIMPLIFY THE PROBLEM
* READ THE STATEMENT CAREFULLY
!!! if there is an specified/interesting smth(i.e. constraint) in the statement,
then you must be careful about that
*/
const int N = 5e5 + 5;
vector<int> v[N],cur[2],vis(N,0);
void dfs(int c,int col){
cur[col].pb(c);
vis[c]=1;
for(int x:v[c]){
if(vis[x]) continue;
dfs(x,!col);
}
}
void solve(){
int n,m;
cin >> n >> m;
for(int i=0;i<m;i++){
int a,b;
cin >> a >> b;
v[a].pb(b);
v[b].pb(a);
}
vector<int> ans;
for(int i=1;i<=n;i++){
if(vis[i]) continue;
cur[0].clear();cur[1].clear();
dfs(i,0);
if(sz(cur[0])<sz(cur[1])) swap(cur[0],cur[1]);
for(int x:cur[0]) ans.pb(x);
}
cout << sz(ans) << endl;
for(int x:ans) cout << x << " ";
cout << endl;
}
int32_t main(){
cin.tie(0); ios::sync_with_stdio(0);
int t=1;//cin >> t;
while(t--) solve();
return 0;
}
