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: Time Limit Exceeded)

using System;

namespace ABC114_C
{
	internal class Program
	{
		public static void Main(string[] args)
		{
			string n = Console.ReadLine();
			int count = 0;
						
			bool seven = false;
			bool five = false;
			bool three = false;
			bool otherNumber = false;
			
			for (int i = 357; i <= int.Parse(n);)
			{
				string splitNumber = "";
				for (int j = 0; j < i.ToString().Length; j++)
				{
					splitNumber = i.ToString().Substring(j, 1);
					if (splitNumber == "7")
					{
						seven = true;
					}else if (splitNumber == "5")
					{
						five = true;
					}else if (splitNumber == "3")
					{
						three = true;
					}
					else
					{
						otherNumber = true;
						break;
					}
				}
				
				if (seven && five && three)
				{
					if (!otherNumber) count++;
				}

				seven = five = three = otherNumber = false;

				if (splitNumber == "7")
				{
					i += 6;
				}else if (splitNumber == "5")
				{
					i += 2;
				}
				else
				{
					i += 2;
				}
			}
			
			Console.WriteLine(count);
		}
	}
}