def func(S, num):
    ret = 0
    if '3' in S and '5' in S and '7' in S and int(S) <= num:
        ret += 1
    if len(S) == 10:
        return 0
    ret += func(S + '3', num)
    ret += func(S + '5', num)
    ret += func(S + '7', num)
    return ret

print func('', input())