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++14 (GCC 5.4.1) (judge verdict: Accepted)

#include <iostream>
#include <cmath>
#include <vector>
using namespace std;

int main () {
  int n; cin >> n;
  int ans = 0;
  
  for (int mask = 0; mask < (1 << 18); mask++) {
    int num = 0;
    
    for (int i = 0; i < 18; i += 2) {
      int digit = i / 2;
      if (mask & (1 << i) && mask & (1 << i + 1)) num += 7 * pow(10, digit);
      else if (mask & (1 << i + 1)) num += 5 * pow(10, digit);
      else if (mask & (1 << i)) num += 3 * pow(10, digit);
    }
    
    if (num > n) {
      break;
    } else {
      vector<bool> fit(10, false);
      while(num) {
        fit[num % 10] = true;
        num /= 10;
      }
      if (!fit[0] && fit[3] && fit[5] && fit[7]) ans++;
    }
  }
  
  cout << ans << endl;
}