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: Wrong Answer)

#include <iostream>
using namespace std;
 
int N;
 
int func(int n, bool has_3, bool has_5, bool has_7) {
  if(n>N) {
    return 0;
  }
  
  int res = 0;
  if (has_3==true && has_5==true && has_7==true) {
    res += 1;
  }
  
  res += func(n*10+3, true, has_5, has_7);
  res += func(n*10+5, has_3, true, has_7);
  res += func(n*10+7, has_3, has_5, true);
 
  return res;
}
 
int main (){
  cin >> N;
  
  cout << func(0, false, false, false) << endl;
  
  return 0;
}