#!/bin/python

import sys


n = int(raw_input())
same_x = 0
same_y = 0
(x,y) = map(int,raw_input().strip().split(' '))
for i in range(n-1):
    (x1,y1) = map(int,raw_input().strip().split(' '))
    if x1 == x:
        same_x +=1
    if y1 == y:
        same_y += 1
if same_x== n-1 or same_y ==n-1:
    print 'YES'
else: print 'NO'