#include <atcoder/all>
#include <iostream>

using namespace std;
using namespace atcoder;

int main() {
    int N;
    cin >> N;

    vector<pair<int, int>> birthdays(N);
    for (int i = 0; i < N; i++) {
        cin >> birthdays[i].first >> birthdays[i].second;
    }

    vector<vector<bool>> check(1001, vector<bool>(1001, false));
    for (int i = 0; i < N; i++) {
        int a = birthdays[i].first;
        int b = birthdays[i].second;
        if (check[a][b]) {
            cout << "Yes" << "\n";
            return 0;
        }
        check[a][b] = true;
    }

    cout << "No" << "\n";

    return 0;
}