#include <bits/stdc++.h>
using namespace std;
//#define int long long
//#define pii pair<long long, long long>
union Ans {
bool b;
vector<int> v;
Ans(bool b) : b(b) {}
Ans(vector<int> v) : v(v) {}
~Ans() {}
Ans(const Ans&) {}
};
Ans n2(int n, int M, vector<int> U, vector<int> V) {
vector<int> u0, u1;
for (int i = 0; i < M; i++) {
if (U[i]) u1.push_back(i);
else u0.push_back(i);
}
if (u1.size() > 0 && u0.size() > 1) {
vector<int> ans = {u0[0], u1[0], u0[1], u0[0], u1[0], u0[1]};
return ans;
} else {
return false;
}
}
void dfs(int v, vector<vector<int>> &g, vector<bool> &uu) {
if (uu[v]) return;
uu[v] = 1;
for (int u : g[v]) {
dfs(u, g, uu);
}
}
Ans undirected(int n, int M, vector<int> U, vector<int> V) {
vector<vector<int>> g(n);
for (int i = 0; i < M; i++) {
g[U[i]].push_back(V[i]);
g[V[i]].push_back(U[i]);
}
if (g[0].size() > 1) return true;
vector<bool> uu(n);
dfs(0, g, uu);
for (int i = 0; i < n; i++) {
if (g[i].size() > 2 && uu[i]) return true;
}
return false;
}
Ans find_journey(int n, int M, vector<int> U, vector<int> V) {
if (n == 2) return n2(n, M, U, V);
return undirected(n, M, U, V);
}
#ifdef ONLINE_JUDGE
signed main() {
Ans ans = find_journey(3, 4, {0, 1, 1, 0}, {1, 0, 0, 1});
if (ans.b) {
for (int x : ans.v) cout << x << " ";
cout << "\n";
}
}
#endif
