def resolve():
    nstr = input()
    length = len(nstr)
    n = int(nstr)

    if length == 2:
        print(n//3-3)
        return

    ten_i = [10**i for i in range(length)]

    import itertools
    result = 14 #100//3 - 4*4 -3
    l=[]
    for pattern in itertools.product([0,3,6,9], repeat=length):
        x = sum([teni * ai for teni, ai in zip(ten_i,pattern)])
        
        if x <= n:
            result += 1
            l.append(x)

    print(result)
    
resolve()