#!/bin/python

import sys

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

if xarr.count(xarr[0]) == n or yarr.count(yarr[0]) == n:
    print 'YES'
else:
    print 'NO'