#!/bin/python

import sys


n = int(raw_input().strip())
first = True
eqX = True
eqY = True
for a0 in xrange(n):
    x,y = raw_input().strip().split(' ')
    x,y = [int(x),int(y)]
    if first:
        fx = x
        fy = y
        first = False
    else:
        if x != fx:
            eqX = False
        if y != fy:
            eqY = False
if eqX or eqY:
    print "YES"
else:
    print "NO"