#!/bin/python3

import sys


n = int(input().strip())
a,b = input().strip().split(' ')
a,b = [int(a),int(b)]
p,o = True,True
for a0 in range(n-1):
    x,y = input().strip().split(' ')
    x,y = [int(x),int(y)]
    if (x!=a):
        p=False
    if (y!=b):
        o=False
    if (p==False and o==False ):
        break
if p or o:
    print("YES")
else:
    print("NO")