#!/bin/python
s=input()
xlis=[]
ylis=[]

xt=0
yt=0

for i in range (0,s):
    a=raw_input().split()
    xlis.append(a[0])
    ylis.append(a[1])

for i in range (0,s):
    if xlis[i] == xlis[0]:
        xt=xt+1

for i in range (0,s):
    if ylis[i] == ylis[0]:
        yt=yt+1
if xt == s:
    print "YES"
    quit()

if yt == s:
    print "YES"
    quit()
if xt != s:
    if yt != s:
        print "NO"
        quit()