#include #include using std::cin; using std::cout; const char endl = '\n'; const int N = 2005; int n; std::bitset g[N]; int main() { std::ios::sync_with_stdio(false); cin.tie(nullptr); cin >> n; for (int i = 1; i <= n; i++) { for (int j = 1, x; j <= n; j++) { cin >> x; g[i][j] = x; } } for (int i = 1; i <= n; i++) { for (int j = 1; j <= n; j++) { if (g[j][i]) g[j] |= g[i]; } } for (int i = 1; i <= n; i++) { if (g[i].count() != n) { cout << "NO" << endl; exit(0); } } cout << "YES" << endl; return 0; }