#include <bits/stdc++.h> using namespace std; void fast_io() { ios::sync_with_stdio(false); std::cin.tie(nullptr); } #include <atcoder/dsu> using namespace atcoder; int main() { fast_io(); int m; cin >> m; vector<tuple<int, int, int>> abc; map<pair<int, int>, vector<int>> mp; for (int i = 0; i < m; i++) { int a, b, c; cin >> a >> b >> c; abc.emplace_back(a, b, c); mp[{a, b}].push_back(i); mp[{b, c}].push_back(i); mp[{a, c}].push_back(i); } dsu uf(2 * m); for (auto [k, v] : mp) { if (v.size() > 2) { cout << "NO\n"; return 0; } auto [a, b] = k; if (v.size() == 2) { bool rev[2]; for (int i = 0; i < 2; i++) { auto [x, y, z] = abc[v[i]]; rev[i] = x == a && z == b; } if (rev[0] == rev[1]) { uf.merge(v[0], v[1] + m); uf.merge(v[0] + m, v[1]); } else { uf.merge(v[0], v[1]); uf.merge(v[0] + m, v[1] + m); } } } for (int i = 0; i < m; i++) { if (uf.same(i, i + m)) { cout << "NO\n"; return 0; } } cout << "YES\n"; }