from __future__ import division
n=int(input())
a=[]
b=[]
for i in range(n):
    x=map(int,raw_input().strip().split(' '))
    a.append(x[0])
    b.append(x[1])
if len(set(a))==1 or len(set(b))==1:
    print 'YES'
else:
    print 'NO'