#!/bin/python

import sys

n = int(raw_input().strip())
start_ratio = 0
in_list = []
counter = 0

vertical = False
x_begin = 0
y_begin = 0
for a0 in xrange(n):
    x,y = raw_input().strip().split(' ')
    x,y = [int(x),int(y)]
    if counter == 1:
        if x <> x_begin and y <> y_begin:
            print "NO"
            sys.exit()
        vertical = True if x == x_begin else False
    elif counter > 1:
        if vertical and x <> x_begin:
            print "NO"
            sys.exit()
        if not vertical and y <> y_begin:
            print "NO"
            sys.exit()
    else:
        x_begin = x
        y_begin = y
        start = True
    counter += 1 
print "YES"