#!/bin/python3

import sys


n = int(input().strip())

def f():
    x0,y0 = input().strip().split(' ')
    x0,y0 = [int(x0),int(y0)]
    xs,ys=True,True
    for a0 in range(n-1):
        x,y = input().strip().split(' ')
        x,y = [int(x),int(y)]
        if x != x0:
            xs = False
        if y != y0:
            ys = False
        if not xs and not ys:
            return "NO"
    return "YES"

print(f())