#!/bin/python

import sys

arx = []
ary = []

n = int(raw_input().strip())
for a0 in xrange(n):
    x,y = raw_input().strip().split(' ')
    x,y = [int(x),int(y)]
    arx.append(x)
    ary.append(y)
    
arx.sort()
ary.sort()

if (arx[0] == arx[n-1]) or (ary[0] == ary[n-1]):
    print "YES"
else:
    print "NO"