/* -*- coding: utf-8 -*-
 *
 * 3155.cc:  No.3155 Same Birthday - yukicoder
 */

#include<cstdio>
#include<algorithm>

using namespace std;

/* constant */

const int MAX_A = 1000;
const int MAX_B = 1000;

/* typedef */

/* global variables */

bool used[MAX_A + 1][MAX_B + 1];

/* subroutines */

/* main */

int main() {
  int n;
  scanf("%d", &n);

  for (int i = 0; i < n; i++) {
    int a, b;
    scanf("%d%d", &a, &b);

    if (used[a][b]) { puts("Yes"); return 0; }
    used[a][b] = true;
  }

  puts("No");
  return 0;
}