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: Wrong Answer)

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace C
{
    class Program
    {
        static void Main(string[] args)
        {
            var n = int.Parse(Console.ReadLine());
            var count = 0;

            for (int i = 0; i < n; i++)
            {
                var c = i.ToString().ToCharArray();
                var flag_7 = false;
                var flag_5 = false;
                var flag_3 = false;
                for (int j = 0; j < c.Length; j++)
                {
                    var str = c[j].ToString();
                    if (str == "7" || str == "5" || str == "3")
                    {
                        switch (int.Parse(c[j].ToString()))
                        {
                            case 7:
                                flag_7 = true;
                                break;
                            case 5:
                                flag_5 = true;
                                break;
                            case 3:
                                flag_3 = true;
                                break;
                            default:
                                break;
                        }
                    }
                    else
                    {
                        break;
                    }

                    if (flag_3 && flag_5 && flag_7)
                    {
                        count++;
                    }
                }
            }

            Console.WriteLine(count);
        }
    }
}