import sys
input = sys.stdin.readline
from collections import *

def nand(x, y):
    return 1^(x&y)

def f(l):
    return nand(nand(nand(l[0], l[1]), l[2]), nand(nand(l[3], l[4]), l[5])) == 1

A = list(input().split())

for S in range(1<<6):
    l = []
    
    for i in range(6):
        l.append((S>>i)&1)
    
    ok = True
    
    for i in range(6):
        for j in range(6):
            if A[i]==A[j] and l[i]!=l[j]:
                ok = False
    
    if not ok:
        continue
    
    if f(l):
        exit(print('YES'))

print('NO')