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 {
  public static void main(String[] args) {
    Scanner sc = new Scanner(System.in);
    int n = sc.nextInt();
    String str = String.valueOf(n);
    int s = str.length();
    int[][][][][] dp = new int[s][2][2][2][2];
    int f = Integer.parseInt(String.valueOf(str.charAt(0)));
    if(f < 3) {
      dp[0][0][0][0][1] = 1;
    } else if(f == 3) {
      dp[0][0][0][0][1] = 1;
      dp[0][1][0][0][0] = 1;
    } else if(f < 5) {
      dp[0][0][0][0][1] = 1;
      dp[0][1][0][0][1] = 1;
    } else if(f == 5) {
      dp[0][0][0][0][1] = 1;
      dp[0][1][0][0][1] = 1;
      dp[0][0][1][0][0] = 1;
    } else if(f < 7) {
      dp[0][0][0][0][1] = 1;
      dp[0][1][0][0][1] = 1;
      dp[0][0][1][0][1] = 1;
    } else if(f == 7) {
      dp[0][0][0][0][1] = 1;
      dp[0][1][0][0][1] = 1;
      dp[0][0][1][0][1] = 1;
      dp[0][0][0][1][0] = 1;
    } else {
      dp[0][0][0][0][1] = 1;
      dp[0][1][0][0][1] = 1;
      dp[0][0][1][0][1] = 1;
      dp[0][0][0][1][1] = 1;
    }

    for(int i = 1; i < s; i++) {
      dp[i][0][0][0][1] = 1;
      for(int j = 0; j < 2; j++) {
        for(int k = 0; k < 2; k++) {
          for(int l = 0; l < 2; l++) {
            dp[i][Math.min(1, j + 1)][k][l][1] += dp[i - 1][j][k][l][1];
            dp[i][j][Math.min(1, k + 1)][l][1] += dp[i - 1][j][k][l][1];
            dp[i][j][k][Math.min(1, l + 1)][1] += dp[i - 1][j][k][l][1];

            int d = Integer.parseInt(String.valueOf(str.charAt(i)));

            if(d < 3) {

            } else if(d == 3) {
              dp[i][Math.min(1, j + 1)][k][l][0] += dp[i - 1][j][k][l][0];
            } else if(d < 5) {
              dp[i][Math.min(1, j + 1)][k][l][1] += dp[i - 1][j][k][l][0];
            } else if(d == 5) {
              dp[i][Math.min(1, j + 1)][k][l][1] += dp[i - 1][j][k][l][0];
              dp[i][j][Math.min(1, k + 1)][l][0] += dp[i - 1][j][k][l][0];
            } else if(d < 7) {
              dp[i][Math.min(1, j + 1)][k][l][1] += dp[i - 1][j][k][l][0];
              dp[i][j][Math.min(1, k + 1)][l][1] += dp[i - 1][j][k][l][0];
            } else if(d == 7) {
              dp[i][Math.min(1, j + 1)][k][l][1] += dp[i - 1][j][k][l][0];
              dp[i][j][Math.min(1, k + 1)][l][1] += dp[i - 1][j][k][l][0];
              dp[i][j][k][Math.min(1, l + 1)][0] += dp[i - 1][j][k][l][0];
            } else {
              dp[i][Math.min(1, j + 1)][k][l][1] += dp[i - 1][j][k][l][0];
              dp[i][j][Math.min(1, k + 1)][l][1] += dp[i - 1][j][k][l][0];
              dp[i][j][k][Math.min(1, l + 1)][1] += dp[i - 1][j][k][l][0];
            }
          }
        }
      }

    }
    
    System.out.println(dp[s - 1][1][1][1][0] + dp[s - 1][1][1][1][1]);
  }
}