Problem:
Score : 300 points

Problem Statement

You are given an integer N. Among the integers between 1 and N (inclusive), how many Shichi-Go-San numbers (literally "Seven-Five-Three numbers") are there?

Here, a Shichi-Go-San number is a positive integer that satisfies the following condition:

When the number is written in base ten, each of the digits 7, 5 and 3 appears at least once, and the other digits never appear.

Constraints

1 \leq N < 10^9

N is an integer.

Input

Input is given from Standard Input in the following format:

N

Output

Print the number of the Shichi-Go-San numbers between 1 and N (inclusive).

Sample Input 1

575

Sample Output 1

4

There are four Shichi-Go-San numbers not greater than 575: 357, 375, 537 and 573.

Sample Input 2

3600

Sample Output 2

13

There are 13 Shichi-Go-San numbers not greater than 3600: the above four numbers, 735, 753, 3357, 3375, 3537, 3557, 3573, 3575 and 3577.

Sample Input 3

999999999

Sample Output 3

26484

Solution in Python (3.4.3) (judge verdict: Accepted)

import numpy as np

N = int(input())
num = ['3', '5', '7']
numbers_753 = []
prev = ['']
for _ in range(9):
    temp = []
    generated = []
    for p in prev:
        for n in num:
            cand = p+n
            generated.append(cand)
            if '3' in cand and '5' in cand and '7' in cand:
                temp.append(int(p+n))
    numbers_753 += temp
    prev = generated
numbers_753 = np.array(numbers_753)
print(sum(numbers_753 <= N))