#!/bin/python

import sys

h_set = set()
v_set = set()
n = int(raw_input().strip())
for a0 in xrange(n):
    x,y = raw_input().strip().split(' ')
    x,y = [int(x),int(y)]
    h_set.add(x)
    v_set.add(y)

if len(h_set)==1 or len(v_set)==1:
    print "YES"
else:
    print "NO"