#!/bin/python

import sys


n = int(raw_input().strip())
list0 = []
list1 = []
for a0 in xrange(n):
    x,y = raw_input().strip().split(' ')
    x,y = [int(x),int(y)]
    list0.append(x)
    list1.append(y)
list0 = set(list0)
list1 = set(list1)
if len(list0) == 1:
    print "YES"
elif len(list1) == 1:
    print "YES"
else:
    print "NO"