#!/bin/python

import sys


n = int(raw_input().strip())
xyes = True
yyes = True
for a0 in xrange(n):
    x,y = raw_input().strip().split(' ')
    x,y = [int(x),int(y)]
    if a0>0:
        if x != xprev:
            xyes = False
        if y != yprev:
            yyes = False
    xprev = x
    yprev = y
if (xyes or yyes):
    print "YES"
else:
    print "NO"