#!/bin/python

import sys


n = int(raw_input().strip())
a=[]
b=[]
for a0 in xrange(n):
    x,y = raw_input().strip().split(' ')
    x,y = [int(x),int(y)]
    a.append(x)
    b.append(y)
a=set(a)
b=set(b)
if len(a)==1 or len(b)==1:
    print 'YES'
else :
    print 'NO'