#include <bits/stdc++.h>
using namespace std;

void solve() {
        int N;
        cin >> N;
        vector<array<string, 2>> A(N);
        bool ok = true;
        for (int i = 0; i < N; i++) {
                cin >> A[i][0] >> A[i][1];
        }
        for (int i = 0; i < N; i++) {
                int cnt_f = 0, cnt_s = 0;
                for (int j = 0; j < N; j++) {
                        if (i != j) {
                                if (A[j][0] == A[i][0] || A[j][1] == A[i][0]) cnt_f++;
                                if (A[j][1] == A[i][1] || A[j][0] == A[i][1]) cnt_s++;
                        }
                }
                if (cnt_f && cnt_s) {
                        ok = false;
                        break;
                }
        }
        cout << (ok ? "Yes\n" : "No\n");
}

int main() {
        ios::sync_with_stdio(false);
        cin.tie(NULL);

        int t = 1;
        // cin >> t;
        while (t--) solve();

        return 0;
}