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.PriorityQueue;
import java.util.Scanner;

public class Main {

	public static void main(String[] args) {
		// TODO Auto-generated method stub
		Scanner sc = new Scanner(System.in);

		int n = sc.nextInt();

		for(int i = 1; i <= 9; i++){
			dfs(0, i);
		}

		int count = 0;
		while(!pq.isEmpty()){
//			System.out.print(pq.poll() + " ");
			if(pq.poll() <= n){
				count++;
			}
			else {
				break;
			}
		}

		System.out.println(count);


	}

	static int digits[] = new int[10];
	static PriorityQueue<Integer> pq = new PriorityQueue<Integer>();

	static void dfs(int depth, int n){
		String tmp = "";

		if(depth == n){
			int appear[] = new int[10];
			for(int i = 0; i < n; i++){
				tmp += (char)(digits[i] + '0');
				appear[digits[i]]++;
			}
			if(appear[3]*appear[5]*appear[7] != 0){
				pq.add(Integer.parseInt(tmp));
			}

			return;
		}

		int pattern[] = {3,5,7};

		for(int i = 0; i < pattern.length; i++){
			digits[depth] = pattern[i];
			dfs(depth + 1, n);
		}
	}
}