#!/bin/python

import sys


n = int(raw_input().strip())
x,y = raw_input().strip().split(' ')
x,y = [int(x),int(y)]
X=True
Y=True
Out="YES"
for a0 in xrange(n-1):
    x0,y0 = raw_input().strip().split(' ')
    x0,y0 = [int(x0),int(y0)]
    if X:
        X = x==x0
    if Y:
        Y = y==y0
    if not X and not Y:
        Out = "NO"
        break
print Out