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

int main() {
  int N; cin >> N;
  vector BD(1001, vector<bool>(1001));
  for (int i = 0; i < N; i++) {
    int A, B; cin >> A >> B;
    if (BD.at(A).at(B)) {
      cout << "Yes" << endl;
      return 0;
    }
    BD.at(A).at(B) = true;
  }
  cout << "No" << endl;
}