#!/bin/python

import sys


n = int(raw_input().strip())
a,b = raw_input().strip().split(' ')
a,b = [int(a),int(b)]
f = True
for a0 in xrange(n-1):
    x,y = raw_input().strip().split(' ')
    x,y = [int(x),int(y)]
    if(a-x!=0 and b-y!=0):
        f = False
print "YES" if f else "NO"