#!/bin/python3

import sys


n = int(input().strip())
hori, verti = True, True
h, v = None, None
while n > 0:
    
    x, y = list(map(int, input().split()))
    if h == None:
        h = x
        v = y
    else:
        if x != h: hori  = False
        if y != v: verti = False
    
    n -= 1
if hori or verti:
    print("YES")
else:
    print("NO")