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 C# (Mono 4.6.2.0) (judge verdict: Accepted)

using System;
using System.Collections.Generic;
using System.Linq;

class Program
{
    private static int _limit;

    private readonly static string[] targets = new string[] {"3", "5", "7"};

    static void Main()
    {
        _limit = int.Parse(Console.ReadLine());
        
        Console.WriteLine(Search(0));
    }

    static long Search(long num)
    {
        if (num > _limit)
        {
            return 0;
        }

        var str = num.ToString();
        long count = 0;

        if (str.Contains("3") && str.Contains("5") && str.Contains("7"))
        {
            count++;
        }
        
        foreach (var target in targets)
        {
            count += Search(long.Parse(str + target));
        }

        return count;
    }
}