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 (Clang 3.8.0) (judge verdict: Accepted)

#include <stdio.h>
int main(int argc, char const *argv[])
{
    unsigned long num753;
    int i, n, nc, keta;
    int ans = 0;
    int c7, c5, c3;
    num753 = i = 0;
    scanf("%d", &n);
    while (1)
    {
        i++;
        nc = i;
        num753 = 0;
        keta = 1;
        c3 = c5 = c7 = 0;
        const int sinsu = 4;
        for (; nc;)
        {
            switch (nc % sinsu)
            {
            case 0:
                // putchar('N');
                goto out;
            case 1:
                num753 += 3 * keta;
                c3 = 1;
                break;
            case 2:
                num753 += 5 * keta;
                c5 = 1;
                break;
            case 3:
                num753 += 7 * keta;
                c7 = 1;
                break;
            }
            nc /= sinsu;
            keta *= 10;
        }
        if(num753 > n){
            break;
        }
        if (c3 + c5 + c7 == 3)
        {
            ans++;
            // printf("%ld\t", num753);
        }
    out:;
    }
    printf("%d\n", ans);
    return 0;
}