#!/bin/python

import sys

flagnotx = 0
flagnoty = 0
n = int(raw_input().strip())
x,y = raw_input().strip().split(' ')
xref,yref = [int(x),int(y)]
for a0 in xrange(n-1):
    x,y = raw_input().strip().split(' ')
    x,y = [int(x),int(y)]
    if x!=xref:
        flagnotx = 1;
    if y!=yref:
        flagnoty = 1;
if flagnotx == 1 and flagnoty ==1:
    print "NO"
else:
    print "YES"