#include <bits/stdc++.h> #include <atcoder/all> using namespace std; using ll = long long; int main(){ ios::sync_with_stdio(false); cin.tie(0); int m, a, b, c; cin >> m; vector<pair<ll,int>> ca(3 * m); for(int i = 1, ci = 0; i <= m; i++){ cin >> a >> b >> c; ca[ci++] = {(ll)(a) << 30 | b, i}; ca[ci++] = {(ll)(b) << 30 | c, i}; ca[ci++] = {(ll)(a) << 30 | c, -i}; } sort(ca.begin(), ca.end()); atcoder::dsu uf(2 * ++m); auto add = [&](int u, int v, int d){ if(d >= 0)uf.merge(u, v), uf.merge(u + m, v + m); else uf.merge(u + m, v), uf.merge(u, v + m); if(uf.same(u, u + m)) cout << "NO\n", exit(0); }; for(int i = 0; i + 1 < ca.size(); i++){ auto [k1, v] = ca[i]; if(i + 2 < ca.size() && k1 == ca[i + 2].first) cout << "NO\n", exit(0); auto [k2, u] = ca[i + 1]; if(k1 == k2)add(abs(v), abs(u), v ^ u ^ -1); } cout << "YES\n"; }