#!/bin/python

import sys
cx=[]
cy=[]
f=0
n = int(raw_input().strip())
for a0 in xrange(n):
    x,y = raw_input().strip().split(' ')
    x,y = [int(x),int(y)]
    cx.append(x)
    cy.append(y)
x=cx[0]
y=cy[0]
cox=cx.count(x)
coy=cy.count(y)
if(cox==n or coy==n):
    print "YES"
else:
    print "NO"