#!/bin/python

import sys


n = int(raw_input().strip())
x, y = map(int, raw_input().split())
x_cnt = 0
y_cnt = 0
x1 = x
y1 = y
for i in range(n-1):
    x, y = map(int, raw_input().split())
    if x1 == x:
        x_cnt += 1
    if y1 == y:
        y_cnt += 1
    x1 = x
    y1 = y
if x_cnt == n-1 or y_cnt == n-1:
    print "YES"
else:
    print "NO"