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 (GCC 5.4.1) (judge verdict: Time Limit Exceeded)

#include <stdio.h>

int n, sum;

int check(int x){
  int f1, f2, f3, y;
  f1 = 0;
  f2 = 0;
  f3 = 0;
  if (x > n) {
    return 0;
  }
  while (x>0) {
    y = x % 10;
    if (y == 7) {
      f1 = 1;
    }
    else if (y == 5) {
      f2 = 1;
    }
    else if (y == 3) {
      f3 = 1;
    }
    x = x / 10;
  }
  if (f1 == 1 && f2 == 1 && f3 == 1) {
    sum++;
  }

  return 0;
}

void func(int x){
  int a, b, c;
  a = x * 10 + 3;
  b = x * 10 + 5;
  c = x * 10 + 7;
  if (a <= n) {
    func(a);
  }
  if (b <= n) {
    func(b);
  }
  if (c <= n) {
    func(c);
  }
  check(a);
  check(b);
  check(c);
}

int main(void){
  sum = 0;

  scanf("%d", &n);

  func(3);
  func(5);
  func(7);

  printf("%d\n", sum);

  return 0;
}