#!/bin/python

import sys


n = int(raw_input().strip())
c1=0
c2=0
list1=[]
list2=[]
for a0 in xrange(n):
    x,y = raw_input().strip().split(' ')
    x,y = [int(x),int(y)]
    list1.append(x)
    list2.append(y)
for a0 in xrange(0,n):
    if(list1[0]==list1[a0]):
        c1=c1+1
    if(list2[0]==list2[a0]):
        c2=c2+1
    
if(c1==n or c2==n):
    print "YES"
else:
    print "NO"
    
c1=0
c2=0