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 main(void){
  long int n;
  int flag1, flag2, flag3, flag4, x, j;
  int y, sum, i;

  scanf("%ld", &n);

  flag1 = 0;
  flag2 = 0;
  flag3 = 0;
  flag4 = 0;
  sum = 0;

  for (i = 1; i <= n; i++) {
    x = i;
    flag1 = 0;
    flag2 = 0;
    flag3 = 0;
    flag4 = 0;
    while(x>0) {
      y = x % 10;
      if (y == 7) {
        flag1 = 1;
      }
      else if (y == 5) {
        flag2 = 1;
      }
      else if (y == 3) {
        flag3 = 1;
      }
      else {
        flag4 = 1;
        break;
      }
      x = x / 10;
    }
    if (flag1 == 1 && flag2 == 1 && flag3 == 1 && flag4 == 0){
    sum++;
    }
  }

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

  return 0;
}