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.Collections.Generic;

namespace abc114_c
{
	class Program
	{
		static void Main(string[] args)
		{
			List<string>[] list = new List<string>[10];
			list[0] = new List<string> { "" };
			for (int i = 1; i < 10; i++)
			{
				list[i] = new List<string>();
				foreach (var item in list[i - 1])
				{
					list[i].Add(item + "3"); list[i].Add(item + "5"); list[i].Add(item + "7");
				}
			}
			int n = int.Parse(Console.ReadLine());
			int ret = 0;
			for (int i = 3; i < 10; i++)
			{
				foreach (var item in list[i])
				{
					int a = 0; int b = 0; int c = 0;
					for (int j = 0; j < item.Length; j++)
					{
						switch (item[j])
						{
							case '3': { a++; break; }
							case '5': { b++; break; }
							case '7': { c++; break; }
						}
					}
					if (int.Parse(item) <= n && a > 0 && b > 0 && c > 0) ret++;
				}
			}
			Console.WriteLine(ret);
		}
	}
}