#include <bits/stdc++.h>
#include "islands.h"
using namespace std;
#define fi first
#define se second
#define pb push_back
const int nax = 1e5+5;
multiset<int> adj[nax];
multiset<int> revadj[nax];
int outdeg[nax];
bool vis[nax];
bool nabba[nax];
bool test=false;
void dfs(int x){
if(vis[x]) return;
vis[x]=true;
for(auto u: adj[x]) dfs(u);
}
void dfs1(int x){
//cout <<x<<endl;
if(nabba[x]) return;
if(outdeg[x]>1) return;
nabba[x]=true;
if(outdeg[x]==1){
for(auto u:revadj[x]){
adj[u].erase(adj[u].count(x));
outdeg[u]--;
}
}
for(auto u:adj[x]) dfs1(u);
}
std::variant<bool, std::vector<int>> find_journey(int N, int M, std::vector<int> U, std::vector<int> V) {
int n = N;
int m = M;
for(int i = 0;i < m ; i++)
{
outdeg[U[i]]++;
adj[U[i]].insert(V[i]);
revadj[V[i]].insert(U[i]);
}
queue<int> q;
for(int i = 0;i < n;i++) if(outdeg[i]==0) q.push(i);
while(!q.empty()){
int x = q.front();
q.pop();
for(auto u : revadj[x]){
adj[u].erase(adj[u].count(x));
outdeg[u]--;
if(outdeg[u]==0) q.push(u);
}
}
dfs(0);
dfs1(0);
for(int i = 0 ;i < n; i++) if(outdeg[i]>=2&&vis[i]&&!nabba[i]) test=true;
return test;
}
