#!/bin/python

import sys


n = int(raw_input().strip())
same_x = True
same_y = True
(last_x, last_y) = (None, None)
for a0 in xrange(n):
    x,y = raw_input().strip().split(' ')
    x,y = [int(x),int(y)]
    if last_x != None and last_x != x:
        same_x = False
    if last_y != None and last_y != y:
        same_y = False
    last_x, last_y = (x, y)
    
if same_x or same_y:
    print "YES"
else:
    print "NO"