#include "islands.h"
#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
const ll N=1e5;
vector<ll> g[N], rg[N];
vector<ll> s;
bool vis[N]={};
void dfs1(ll curr){
if(vis[curr]) return;
vis[curr]=1;
for(auto nxt:g[curr]){
dfs1(nxt);
}
s.push_back(curr);
}
ll scc[N], sz[N];
void dfs2(ll curr, ll x){
if(scc[curr]!=-1) return;
scc[curr]=x;
sz[x]++;
for(auto nxt:rg[curr]){
dfs2(nxt,x);
}
}
vector<ll> dag[N+1];
ll c[N+1]={};
void dfs3(ll curr){
if(c[curr]!=-1) return;
c[curr]=0;
for(auto nxt:dag[curr]){
dfs3(nxt);
c[curr]+=c[nxt];
}
}
variant<bool, vector<int>> find_journey(int n, int m, vector<int> u, vector<int> v) {
for(ll i=0; i<m; i++){
g[u[i]].push_back(v[i]);
rg[v[i]].push_back(u[i]);
}
for(ll i=0; i<n; i++){
dfs1(i);
scc[i]=-1;
}
reverse(s.begin(),s.end());
for(auto i:s){
// cout<<i<<endl;
dfs2(i,i);
}
for(ll i=0; i<m; i++){
if(scc[u[i]]!=scc[v[i]] && u[i]!=0) dag[scc[v[i]]].push_back(scc[u[i]]);
}
for(ll i=0; i<m; i++){
if(u[i]==0) dag[scc[v[i]]].push_back(n);
}
// for(ll i=0; i<n; i++){
// cout<<scc[i]<<" ";
// }
// cout<<endl;
for(ll i=0; i<n; i++){
c[i]=-1;
}
c[n]=1;
bool ans=0;
for(ll i=0; i<n; i++){
dfs3(i);
// cout<<sz[i]<<" "<<c[i]<<endl;
if(sz[i]>1 && c[i]>=2) ans=1;
}
return ans;
}
