#!/bin/python

import sys


n = int(raw_input().strip())
xx = None
horizontal = True
yy = None
vertical = True
for a0 in xrange(n):
    x,y = raw_input().strip().split(' ')
    x,y = [int(x),int(y)]
    if not xx:
        xx = x
        yy = y
    else:
        if x != xx:
            vertical = False
        if y != yy:
            horizontal = False
        if not horizontal and not vertical:
            print "NO"
            break
if horizontal or vertical:
    print "YES"