#include <iostream>
#include <string>

using namespace std;

int main() {
    int n;
    cin >> n;
    string s[n], t[n];
    for (int i = 0; i < n; i++) {
        cin >> s[i] >> t[i];
    }

    bool ans = true;
    for (int i = 0; i < n; i++) {
        bool fs = true, ft = true;
        for (int j = 0; j < n; j++) {
            if (i == j) {
                continue;
            }

            if (s[i] == s[j] || s[i] == t[j]) {
                fs = false;
            }
            if (t[i] == s[j] || t[i] == t[j]) {
                ft = false;
            }
        }

        if (!fs && !ft) {
            ans = false;
        }
    }

    cout << (ans ? "Yes" : "No") << endl;

    return 0;
}