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.IO;
using System.Linq;
using System.Text;
using System.Text.RegularExpressions;

namespace AtCoder
{
	public class ABC
	{
		static int mod = 1000000007;  // 10^9+7

		static void Main(string[] args)
		{
			Console.SetOut(new StreamWriter(Console.OpenStandardOutput()) { AutoFlush = false });


			int n = int.Parse(Console.ReadLine());
			//string s = Console.ReadLine();
			//int[] vs = Console.ReadLine().Split().Select(int.Parse).ToArray();
			//long[] vs = Console.ReadLine().Split().Select(long.Parse).ToArray();
			int ans = saiki(n, 0, false, false, false);
			Console.WriteLine(ans);


			Console.Out.Flush();
		}

		static int saiki(int n, int x, bool f3, bool f5, bool f7)
		{
			int result = 0;
			if (f3 && f5 && f7) {
				result++;
			}
			//System.Diagnostics.Debug.WriteLine($"{x} {f3 && f5 && f7}");

			long i = (long)x * 10 + 3;
			if (i <= n) { result += saiki(n, (int)i, true, f5, f7); }
			i = (long)x * 10 + 5;
			if (i <= n) { result += saiki(n, (int)i, f3, true, f7); }
			i = (long)x * 10 + 7;
			if (i <= n) { result += saiki(n, (int)i, f3, f5, true); }

			return result;
		}
	}
}