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: Accepted)

#include<stdio.h>

long int func(long int n,long int a){
  long int ans=0,t,flag1=0,flag2=0,flag3=0;
  t=n;

  if(n>a) return 0;
  
  while(t>0){
    if(t%10==7) flag1=1;
    else if(t%10==5) flag2=1;
    else if(t%10==3) flag3=1;
    if((flag1+flag2+flag3)==3){
      ans=1;
      break;
    }
    t/=10;
  }
  ans+=func(10*n+3,a);
  ans+=func(10*n+5,a);
  ans+=func(10*n+7,a);
  
  return ans;
}

int main(void){
  long int ans,n;    
  scanf("%ld",&n);
  ans = func(0,n);
  printf("%ld",ans);
  return 0;
}