#include "islands.h"
#include <variant>
#include <vector>
#include <bits/stdc++.h>
using namespace std;
#define pb push_back
std::variant<bool, std::vector<int>> find_journey(
int N, int M, std::vector<int> U, std::vector<int> V) {
int n = N, m = M;
// subtask #3
vector <vector<int>> adj(n);
for ( int i = 0; i < m; i++ ){
adj[U[i]].pb(V[i]);
}
bool has = false;
vector <int> us(n);
auto dfs = [&](auto dfs, int u, int p) -> void{
bool vis = false;
us[u] = 1;
for ( auto &v: adj[u] ){
if ( v == p && !vis ){
vis = true;
continue;
}
if ( !us[v] ){
dfs(dfs, v, u);
} else has = true;
}
};
dfs(dfs, 0, -1);
return has;
}
