#!/bin/python3

import sys


n = int(input().strip())
dictX = {}
dictY = {}
for a0 in range(n):
    x,y = input().strip().split(' ')
    x,y = [int(x),int(y)]
    if x not in dictX:
        dictX[x] = 1
    else:
        dictX[x] += 1
    if y not in dictY:
        dictY[y] = 1
    else:
        dictY[y] += 1

ans = "NO"
for key,value in dictX.items():
    if value == n:
        ans = "YES"
for key,value in dictY.items():
    if value == n:
        ans = "YES"

print(ans)