#!/bin/python

import sys


n = int(raw_input().strip())
lx=[]
ly=[]
for a0 in xrange(n):
    x,y = raw_input().strip().split(' ')
    x,y = [int(x),int(y)]
    lx.append(x)
    ly.append(y)
xstate=True
ystate=True

for i in xrange(n-1):
    if not lx[i]==lx[i+1]:
        xstate=False
    if not ly[i]==ly[i+1]:
        ystate=False
if xstate or ystate:
    print 'YES'
else:
    print 'NO'