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 static Atcoder;
using System.Threading.Tasks;
using System.ComponentModel;

public class Hello
{

    public static void Main()
    {
        int N = intRead();
        List<int> list = new List<int>();
        List<int> anslist = new List<int>();
        List<int> newlist = new List<int>();
        newlist.Add(3);
        newlist.Add(5);
        newlist.Add(7);
        int ans = 0;
        for (int i = 1; i < N.ToString().Length; i++)
        {
            foreach (int l in newlist)
            {
                list.Add(int.Parse(l.ToString() + "3"));
                list.Add(int.Parse(l.ToString() + "5"));
                list.Add(int.Parse(l.ToString() + "7"));
                anslist.Add(int.Parse(l.ToString() + "3"));
                anslist.Add(int.Parse(l.ToString() + "5"));
                anslist.Add(int.Parse(l.ToString() + "7"));
            }
            newlist = new List<int>(list);
            list = new List<int>();
        }
        anslist.Sort();
        for (int i = 0; i < anslist.Count(); i++)
        {
            if (anslist[i] <= N)
            {
                if (anslist[i].ToString().Count(c => c == '3') > 0 &&
                    anslist[i].ToString().Count(c => c == '5') > 0 &&
                    anslist[i].ToString().Count(c => c == '7') > 0) ans++;
            }
        }
        Console.WriteLine(ans);
    }
}


public class Atcoder
{
    static void Swap<T>(ref T a, ref T b)
    {
        var t = a;
        a = b;
        b = t;
    }
    public static long LCM(long a, long b)
    {
        long c = a * b;
        if (a < b) Swap(ref a, ref b);
        long d = a % b;
        while (d != 0)
        {
            a = b;
            b = d;
            d = a % b;
        }
        return c / b;
    }
    public static string strReverce(string s)
    {
        return new string(s.Reverse().ToArray());
    }
    public static int intRead()
    {
        return int.Parse(Console.ReadLine());
    }
    public static bool IsPrime(int n)
    {
        if (n < 2) return false;
        if (n == 2) return true;
        if (n % 2 == 0) return false;

        //double sqrtNum = Math.Sqrt(n);
        for (int i = 3; i < n; i += 2)
        {
            if (n % i == 0) return false;
        }
        return true;
    }
    public static string[] SpRead(char c)
    {
        return Console.ReadLine().Split(c);
    }
    public static int[] SpIntRead(char c)
    {
        return Console.ReadLine().Split(' ').Select(a => int.Parse(a)).ToArray();
    }
    public static string ToConvertBit(int N, int e)
    {
        string ret = "";
        int r = 0;
        while (N != 0)
        {
            r = N % e;
            ret += r.ToString();
            N -= r;
            N /= e;
        }
        ret = strReverce(ret);
        return ret;
    }

}