#!/bin/python3

import sys


n = int(input().strip())
vertical = True
horizontal = True

for a0 in range(n):
    
    x,y = input().strip().split(' ')
    x,y = [int(x),int(y)]
    
    if(a0 == 0):
        lastx = x
        lasty = y
    
    if lastx != x:
        vertical = False
    elif lasty != y:
        horizontal = False
    lastx = x
    lasty = y
if vertical or horizontal:
    print("YES")
else:
    print("NO")