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: Wrong Answer)

import itertools
def calc_num(S,S_len):
    result = 0;
    l = [3,5,7];
    i = 3;
    while i <= S_len:
      for v in itertools.product(l,repeat=i):
        if int("".join(map(str, v))) >= S: 
          break;
        if list(set(v) & set(l)) == l: 
          result = result + 1;
      i = i + 1;
    return result
  
S = list(map(int,input()))
S_len = len(S);
S = int("".join(map(str, S)));
result = calc_num(S,S_len);
print(result)