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.Linq;
using System.Collections.Generic;

class Program
{
    static void Main(string[] args)
    {
        var N = long.Parse(Console.ReadLine());

        int count = GetCount("0", N);
        Console.WriteLine(count);

    }

    static int GetCount(string current, long N)
    {
        if (long.Parse(current) > N)
        {
            return 0;
        }

        var targets = new String[] { "7", "5", "3" };
        int count = 0;

        bool found = true;
        foreach (var ch in targets)
        {
            if (!current.Contains(ch))
            {
                found = false;
                break;
            }
        }

        if (found)
        {
            count++;
        }

        foreach (var ch in targets)
        {
            int currentCount = GetCount(current + ch, N);
            count += currentCount;
        }

        return count;
    }

}