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)

# 2019-11-11 16:07:35(JST)
import sys
# import collections
# import math
# from string import ascii_lowercase, ascii_uppercase, digits
# from bisect import bisect_left as bi_l, bisect_right as bi_r
import itertools
# from functools import reduce
# import operator as op
# from scipy.misc import comb # float
# import numpy as np 

shichigosan = '357'

def main():

    n = int(sys.stdin.readline().rstrip())
    
    count = 0
    for i in range(3, len(str(n)) + 1):
        sub_shichigosan = list(''.join(s) for s in itertools.product(shichigosan, repeat=i))
        for sub in sub_shichigosan:
            for d in shichigosan:
                if d in sub:
                    continue
                else:
                    break
            else:
                if 357 <= int(sub) <= n:
                    count += 1
    
    print(count)

if __name__ == "__main__":
    main()