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;
class Asf{public static long n;
          public static long score=0;
  public static void DFS(string str)
  {
    if(long.Parse(str)>n){return;}
    bool ok=true;bool []s=new bool [3];
    for(int i=1;i<str.Length;i++){if(str[i]!='3'&&str[i]!='5'&&str[i]!='7'){ok=false; break;}
                                 if(str[i]=='3'){s[0]=true;}if(str[i]=='7'){s[2]=true;}
                                  if(str[i]=='5'){s[1]=true;}
                                 }
	if(ok&&s[0]&&s[1]&&s[2]){score++;}
    for(int i=0;i<3;i++){
  DFS(str+(3+2*i).ToString());
  
    }
  return ;
  }
static void Main(){
n=long.Parse(Console.ReadLine());
DFS("0");
  Console.WriteLine(score);
}
}