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;
class P{
public static List<long> a=new List<long>();
  static void Main(){
     long n=long.Parse(Console.ReadLine());
     foreach(long x in new long[]{3,5,7})b(x,n);
     Console.WriteLine(a.Count(x=>3==x.ToString().ToCharArray().Distinct().Count()));
  }
  static void b(long num,long lim){
    if(num<=lim){
      a.Add(num);
      b(num*10+3,lim);
      b(num*10+5,lim);
      b(num*10+7,lim);
    }
  }
}