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.Collections;
using System.Collections.Generic;
using System.ComponentModel;
using System.IO;
using System.IO.Pipes;
using System.Linq;
using System.Numerics;
using System.Text;
using System.Threading.Tasks;

namespace AtCorders
{
	public class Program
	{
		static void Main(string[] args)
		{
			string n = Console.ReadLine();
			int l = n.Length;

			int bitmax = 1 << 3;
			var dp0 = new long[l];
			var dp1 = new long[l];
			for (int j = 0; j <= n[0] - '0'; j++) {
				if (j == n[0] - '0') {
					if (j == 3) {
						dp0[0] += 1;
					} else if (j == 5) {
						dp0[0] += 1;
					} else if (j == 7) {
						dp0[0] += 1;
					} else {
						dp0[0] += 1;
					}
				} else {
					if (j == 3) {
						dp1[0] += 1;
					} else if (j == 5) {
						dp1[0] += 1;
					} else if (j == 7) {
						dp1[0] += 1;
					} else {
						dp1[0] += 1;
					}
				}
			}

			for (int i = 1; i < l; i++) {
				int nn = n[i] - '0';
				dp1[i] = dp1[i - 1] * 3;
				for (int j = 0; j <= 9; j++) {
						if (j == 3) {
							if (j < nn) {
								dp1[i] += dp0[i - 1];
							}
							if (j == nn) {
								dp0[i] += 1;
							}
						} else if (j == 5) {
							if (j < nn) {
								dp1[i] += dp0[i - 1];
							}

							if (j == nn) {
								dp0[i] += 1;
							}
						} else if (j == 7) {
							if (j < nn) {
								dp1[i] += dp0[i - 1];
							}

							if (j == nn) {
								dp0[i] += 1;
							}
						} else {
							dp1[i] += dp1[i - 1];
							if (j < nn) {
								dp1[i] += dp0[i - 1];
							}

							if (j == nn) {
								dp0[i] += 1;
							}
						}
				}
			}

			long ans = dp0[l - 1] + dp1[l - 1];
			Console.WriteLine(ans);
		}
	}
}