#!/bin/python

import sys


n = int(raw_input().strip())
L1=[]
L2=[]

for a0 in xrange(n):
    x,y = raw_input().strip().split(' ')
    x,y = [int(x),int(y)]
    L1.append(x)
    L2.append(y)
    s1=set(L1)
    s2=set(L2)
if(len(s1)==1 ):
    print "YES"
elif(len(s2)==1):
    print "YES"
else: print "NO"