#!/bin/python

import sys

vLine = True
hLine = True
ax = None
ay = None

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

    if not ax:
        ax = x
        ay = y
    else:
        if ax != x and vLine:
            vLine = False
        if ay != y and hLine:
            hLine = False
if vLine or hLine:
    print 'YES'
else:
    print 'NO'