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;

class Program
{
    static void Main(string[] args)
    {
        var n = int.Parse(Console.ReadLine());
        var ans = m1(0, n);
        Console.WriteLine(ans);
    }

    static int[] d = new[] { 7, 5, 3 };
    static int m1(int x, int max)
    {
        var sum = m2(x) ? 1 : 0;
        for (int i = 0; i < 3; i++)
        {
            var n = 10 * x + d[i];
            if (0 < n && n <= max)
            {
                sum += m1(n, max);
            }
        }
        return sum;
    }

    static bool m2(int x)
    {
        var s = x.ToString();
        return s.Contains('7') && s.Contains('5') && s.Contains('3');
    }
}