#!/usr/bin/env/ python
# -*- coding:utf-8 -*-

N = raw_input()
N = int(N)
rc = []

for i in range(N):
    ra,ca,rb,cb = raw_input().split()
    ra = int(ra)
    ca = int(ca)
    rb = int(rb)
    cb = int(cb)
    rc.append([ra,ca])
    rc.append([rb,cb])

#print rc

rc_uniq = []
for x in rc:
    if x not in rc_uniq:
        rc_uniq.append(x)

#print rc_uniq
        
if N <= len(rc_uniq):
    print 'YES'
else:
    print 'NO'