#!/bin/python3

import sys

currentX = -100
currentY = -100
isGood = "YES"

n = int(input().strip())
for a0 in range(n):
    x,y = input().strip().split(' ')
    x,y = [int(x),int(y)]

    if currentX == -100 or currentY == -100:
        currentX = x
        currentY = y
    elif (x > currentX or x < currentX) and (y > currentY or y < currentY):
        isGood = "NO"
    
print(isGood)