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

int main()
{
    int N;
    cin >> N;
    vector<set<int>> mon(1001);
    while (N--) {
        int a, b;
        cin >> a >> b;
        if (mon[a].contains(b)) {
            cout << "Yes" << endl;
            return 0;
        } else {
            mon[a].insert(b);
        }
    }
    cout << "No" << endl;
}