#!/bin/python

import sys


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

if(max(my_x)==min(my_x)):
    print "YES"
elif (max(my_y)==min(my_y)):
    print "YES"
else:
    print "NO"