#!/bin/python

import sys

input_list=[]
n = int(raw_input().strip())
for a0 in xrange(n):
    x,y = raw_input().strip().split(' ')
    x,y = [int(x),int(y)]
    input_list.append([x,y])
    
element1 = input_list[0]
countx=0
county=0
for ele in input_list:
    if element1[0]==ele[0]:
        countx+=1 
    if element1[1]==ele[1]:
        county+=1
    
if countx==n or county==n:
    print "YES"
else:
    print "NO"