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>
int main(void){
   int v;
   int n;
   int b[3];
   scanf("%d\n",&n);
   int ans=0;
   long long e[15],f[15];
   int a[10];
   e[0]=1;f[0]=1;
   for(int i=1;i<15;i++)e[i]=10*e[i-1];
   for(int i=1;i<15;i++)f[i]=3*f[i-1];
   for(int g=1;g<10;g++){
   for(int i=0;i<f[g];i++){
       v=i;
       for(int i=0;i<g;i++){
           a[i]=v%3;
           v-=v%3;
           v/=3;
       }b[0]=0;b[1]=0;b[2]=0;
       for(int i=0;i<g;i++){
           b[a[i]]++;
       }
       if(b[0]&&b[1]&&b[2]){
            v=0;
            for(int i=0;i<g;i++){
                v+=(a[i]*2+3)*e[i];
            }
            if(v<=n)ans++;
       }
   }
   }
   printf("%d\n",ans);
}