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.Text;
using static System.Console;
namespace a755
{
    class a755
    {
        static void Main(string[] args)
        {
            long x = long.Parse(ReadLine());
            long op = 0;
            long c = 357;
            while (c <= x)
            {
                bool hit3 = false;
                bool hit5 = false;
                bool hit7 = false;
                bool hitX = false;

                for (int i = 1; (long)Math.Pow(10, i - 1) <= c; i++)
                {
                    IsNumber357((c - c / (long)Math.Pow(10, i) * (long)Math.Pow(10, i)) / (long)Math.Pow(10, i - 1), ref hit3, ref hit5, ref hit7, ref hitX);
                    if (hitX)
                    {
                        if (i == 1)
                        {
                            c = c + 2;
                            break;
                        }
                        else
                        {
                            c = c + (long)Math.Pow(10, i - 1);
                            break;
                        }
                    }

                }

                if (!hitX)
                {
                    if (hit3 && hit5 && hit7)
                    {
                        op = ++op;
                    }
                    c = c + 2;
                }
            }
            WriteLine(op);
        }

        static void IsNumber357(long c, ref bool hit3, ref bool hit5, ref bool hit7, ref bool hitX)
        {
            switch (c)
            {
                case 3:
                    hit3 = true;
                    break;
                case 5:
                    hit5 = true;
                    break;
                case 7:
                    hit7 = true;
                    break;
                default :
                    hitX = true;
                    break;
            }
        }
    }
}