#!/bin/python3

import sys


n = int(input().strip())
array = []
for a0 in range(n):
    x,y = input().strip().split(' ')
    x,y = [int(x),int(y)]
    array.append((x,y))
    
hori = array[0][0]
verti = array[0][1]

flag = 0
for i in range(len(array)):
    if hori != array[i][0]:
        flag += 1
        break
        
for i in range(len(array)):
    if verti != array[i][1]:
        if flag == 1:
            print ("NO")
            flag += 1
            break
if flag <= 1: print ("YES")