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 Java8 (OpenJDK 1.8.0) (judge verdict: Accepted)

import java.util.*;

public class Main {
    
    static int ans;
    static int N;
    
    public static void main(String[] args) throws Exception {

        Scanner sc = new Scanner(System.in);
        N = sc.nextInt();
        dfs(0L, 0b000);
        System.out.println(ans);
    }
    
    static void dfs( long num, int use ){
        
        if( num > N ){
            return;
        }
        
        if( use == 0b111 ){
            ans++;
        }
        
        dfs( num * 10 + 3, use | 0b001 );
        dfs( num * 10 + 5, use | 0b010 );
        dfs( num * 10 + 7, use | 0b100 );
        
    }
}