#include "islands.h"
#include<bits/stdc++.h>
using namespace std;
typedef long long ll;
typedef pair<int,int> pii;
typedef pair<ll,ll> pll;
void debug_out(){cerr<<endl;}
template<typename Head, typename... Tail>
void debug_out(Head H, Tail... T){
cerr << H << ' ';
debug_out(T...);
}
#define debug(...) cerr << "(" << #__VA_ARGS__ << "): ", debug_out(__VA_ARGS__)
#define F first
#define S second
#define all(x) x.begin(), x.end()
#define MP(x, y) make_pair(x, y)
const int maxn = 1e5 + 10;
int n, m, h[maxn];
vector<pii> g[maxn];
bool vis[maxn];
bool dfs(int v, int p = -1){
int cnt = g[v].size();
if (p != -1) cnt--;
if (cnt == 2) return true;
vis[v] = true;
for (auto [u, w]: g[v]){
if (!vis[u]){
h[u] = h[v] + 1;
if (dfs(u, w)) return true;
}
else if (w != p && h[u] < h[v]){
// debug(v, u);
return true;
}
}
return false;
}
std::variant<bool, std::vector<int>> find_journey(
int N, int M, std::vector<int> U, std::vector<int> V) {
//if (n < 2)
n = N, m = M;
for (int i = 0; i < m; i++){
g[U[i]].push_back({V[i], i/2});
}
return dfs(0);
}
