#include <iostream>
#include <vector>
#include <string>

int main() {
    std::ios_base::sync_with_stdio(false);
    std::cin.tie(NULL);
    int N;
    std::cin >> N;
    std::vector<std::string> S(N), T(N);
    for (int i = 0; i < N; ++i) {
        std::cin >> S[i] >> T[i];
    }

    for (int i = 0; i < N; ++i) {
        bool s_can_use = true;
        for (int j = 0; j < N; ++j) {
            if (i == j) continue;
            if (S[i] == S[j] || S[i] == T[j]) {
                s_can_use = false;
                break;
            }
        }

        bool t_can_use = true;
        for (int j = 0; j < N; ++j) {
            if (i == j) continue;
            if (T[i] == S[j] || T[i] == T[j]) {
                t_can_use = false;
                break;
            }
        }
        
        if (!s_can_use && !t_can_use) {
            std::cout << "No" << std::endl;
            return 0;
        }
    }

    std::cout << "Yes" << std::endl;
    return 0;
}