#!/bin/python3

import sys


n = int(input().strip())

xs, ys = [], []
for a0 in range(n):
    x,y = input().strip().split(' ')
    x,y = [int(x),int(y)]
    xs.append(x)
    ys.append(y)

for i in range(n):
    if xs[i] != xs[0]:
        for j in range(n):
            if ys[j] != ys[0]:
                print('NO')
                break
        else:
            print("YES")
        break
else:
    print("YES")