#!/bin/python

import sys


n = int(raw_input().strip())
x0,y0 = map(int, raw_input().strip().split(' '))
same_x = 1
same_y = 1
on_hor_or_ver_line = True
for i in range(1, n):    
    x,y = map(int, raw_input().strip().split(' '))
    if x == x0:
        same_x += 1
    elif y == y0:
        same_y += 1
    else:        
        break
    
if same_x == n or same_y == n:
    on_hor_or_ver_line = True
else:
    on_hor_or_ver_line = False
if on_hor_or_ver_line: print "YES" 
else: print "NO"