#!/bin/python

import sys

l1=[]
l2=[]
n = int(raw_input().strip())
for a0 in xrange(n):
    x,y = raw_input().strip().split(' ')
    x,y = [int(x),int(y)]
    l1.append(x)
    l2.append(y)
a=l1[0]
b=l2[0]
z,k=True,True
for i in xrange(n):
    if a!=l1[i]:
        z=False
        break
for i in xrange(n):
    if b!=l2[i]:
        k=False
        break
if z==True or k==True:
    print "YES"
else:
    print "NO"