#include using namespace std; #define int long long #define double long double #define vi vector #define vvi vector #define pii pair #define piii pair #define viii vector #define vii vector #define fi first #define se second #define pb push_back const double eps=1e-12; signed main(){ ios_base::sync_with_stdio(0); cin.tie(0); int n; cin >> n; viii v(n); for (int i=0;i> v[i].fi.fi >> v[i].fi.se >> v[i].se; vvi con(n); for (int i=0;i libre(n,1); for (int i=0;i cola; int ca,cb; ca=cb=0; cola.push(i); while (cola.size()){ int x=cola.front(); cola.pop(); if (libre[x]){ if (x==i){ color[i]=1; ca++; } else{ bool a,b; a=b=0; for (int y:con[x]) if (color[y]==1) a=1; for (int y:con[x]) if (color[y]==2) b=1; if (a && b) Q=0; else if (a){ color[x]=2; cb++; } else{ color[x]=1; ca++; } } libre[x]=0; for (int y:con[x]) cola.push(y); } } if (Q && ca!=cb) T=1; } if (T) cout << "YES\n"; else cout << "NO\n"; }