#!/bin/python

import sys


n = int(raw_input().strip())
a = list()
b = list()
for a0 in xrange(n):
    x,y = raw_input().strip().split(' ')
    x,y = [int(x),int(y)]
    a.append(x)
    b.append(y)
a1 = a[0]
isX = True
isY = True
for i in xrange(1,len(a)):
    if a1!=a[i]:
        isX = False
        break
b1 = b[0]
for j in xrange(1,len(b)):
    if b1!=b[j]:
        isY = False
        break
if isX or isY:
    print "YES"
else:
    print "NO"