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 programm
{
    static int res = 0;
    static long N = 0;
    static void Main(string[] args)
    {
        N = long.Parse(Console.ReadLine());
        // dfsの呼び出し
        // 全探索
        // 再帰関数
        dfs("0");
        Console.WriteLine(res);
    }

    static void dfs(string s)
    {
        if (long.Parse(s) > N) return;

        if (0 < s.Count(x => x == '7') && 0 < s.Count(x => x == '5') && 0 < s.Count(x => x == '3'))
        {
            res++;
        }

        foreach (char c in "753")
        {
            dfs(s + c);
        }
    }


}