#!/bin/python3

import sys


n = int(input().strip())
l=[]
for a0 in range(n):
    x,y = input().strip().split(' ')
    x,y = [int(x),int(y)]
    l.append([x,y])
flag1=1
flag2=1
for i in range(n-1):
    if(l[i][0]!=l[i+1][0]):
        flag1=0
    if(l[i][1]!=l[i+1][1]):
        flag2=0
if (flag1==1 or flag2==1):
    print("YES")
else:
    print("NO")