#!/bin/python

import sys

xtrue=True
ytrue=True
x1=0
y1=0
n = int(raw_input().strip())
x,y = raw_input().strip().split(' ')
x,y = [int(x),int(y)]
x1=x
y1=y
    
for a0 in xrange(n-1):
    x,y = raw_input().strip().split(' ')
    x,y = [int(x),int(y)]
    #print x,y
    if x != x1:
        xtrue=False
    
    if y != y1:
        ytrue=False
    
    x1=x
    y1=y
    
    
        
if ytrue or xtrue:
    print "YES"
else:
    print "NO"