#!/bin/python

import sys


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

if len(set(xs)) == 1:
    print "YES"
elif len(set(ys)) == 1:
    print "YES"
else:
    print "NO"