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: Wrong Answer)

using System;
using System.Linq;

class C
{
	static void Main()
	{
		var n = Console.ReadLine();
		var d = n.Length;

		var dp = new int[d + 1, 2];
		dp[0, 0] = 1;
		for (int i = 0; i < d; i++)
		{
			dp[i + 1, 0] = "753".Contains(n[i]) ? dp[i, 0] : 0;
			dp[i + 1, 1] = "753".Count(x => x < n[i]) * dp[i, 0] + 3 * dp[i, 1];
		}
		Console.WriteLine(dp[d, 0] + dp[d, 1]);
	}
}