#!/bin/python

import sys

l = []
n = int(raw_input().strip())
for a0 in xrange(n):
    x,y = raw_input().strip().split(' ')
    x,y = [int(x),int(y)]
    l.append([x, y])
a,b=0,0
for i in range(len(l)):
    if l[i][0]!=l[0][0]:
        a = 1
    if l[i][1]!=l[0][1]:
        b = 1
if a==0 or b==0:
    print('YES')
else:
    print('NO')