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

namespace ABC114 {
	class ABC114_C {
		static void Main(string[] args) {
			var line = Console.ReadLine();
			var list = new List<string>();
			var temp = new List<string>();
			var array = new string[3] {"3", "5", "7", };

			for(int i = 0; i < array.Length; i++)
				for(int j =0; j < array.Length; j++)
					for(int k = 0; k < array.Length; k++)
							list.Add(array[i] + array[j] + array[k]);
			list = list.Distinct().ToList();
			for(int i = array.Length+1; i <= line.Length; i++) {
				foreach (var item in list)
					foreach (var next in array)
						temp.Add(item + next);
				list = list.Concat(temp.Distinct()).Distinct().ToList();
			}

			Console.WriteLine(
				list.Where(s => s.Contains("3") && s.Contains("5") && s.Contains("7"))
				.Select(s => int.Parse(s)).Count(n => n <= int.Parse(line)));

		}
	}
}