#!/usr/bin/env python
#coding:utf8

import itertools


def read():
    return map(int, raw_input().split())


def isKadomatsu(A1, A2, A3):
    return len(set([A1, A2, A3])) == 3 and (A2 > max(A1, A3) or A2 < min(A1, A3))


def work(vList):

    for candi in itertools.permutations(vList, len(vList)):
        isOK = True
        for i in range(len(vList) - 2):
            if not isKadomatsu(candi[i], candi[i + 1], candi[i + 2]):
                isOK = False
                break

        if isOK:
            print "YES"
            return
    
    print "NO"

    
if __name__ == "__main__":
    work(read())