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;

namespace test
{
    class Program
    {
        static void Main(string[] args)
        {
            var N = ReadInt();
            var num = new List<string>();
            num.Add("3");
            num.Add("5");
            num.Add("7");
            for (int i = 1; i < N.ToString().Length; i++)
            {
                var tmp = new List<string>();
                foreach(var n in num)
                {
                    tmp.Add(n + "3");
                    tmp.Add(n + "5");
                    tmp.Add(n + "7");
                }
                foreach (var t in tmp) num.Add(t);
                num = num.Distinct().ToList();
            }
            num = num.Skip(12).ToList();
            var cnt = 0;
            foreach(var n in num)
            {
                var chk = int.Parse(n);
                if (chk > N) continue;
                var three = false;
                var five = false;
                var seven = false;
                while (chk > 0)
                {
                    var tmp = chk % 10;
                    chk /= 10;
                    if (tmp == 3) three = true;
                    else if (tmp == 5) five = true;
                    else if (tmp == 7) seven = true;
                }
                if (three && five && seven) cnt++;
            }
            
            Console.WriteLine(cnt);
            Console.ReadLine();
        }

        static string Read() { return Console.ReadLine(); }
        static int ReadInt() { return int.Parse(Read()); }
        static long ReadLong() { return long.Parse(Read()); }
        static int[] ReadArrayInt() { return Read().Split(' ').Select(s => int.Parse(s)).ToArray(); }
        static long[] ReadArrayLong() { return Read().Split(' ').Select(s => long.Parse(s)).ToArray(); }
    }
}