#include <iostream>
#include <vector>
#include <algorithm>

using namespace std;

int main()
{
  int n;
  cin >> n;
  vector<int> flag(1000000);
  for (int i = 0; i < n; ++i)
  {
    int a, b;
    cin >> a >> b;
    --a, --b;
    a = a * 1000 + b;
    if (flag[a])
    {
      cout << "Yes" << endl;
      return 0;
    }
    flag[a] = 1;
  }
  cout << "No" << endl;
}