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 Kotlin (1.0.0) (judge verdict: Accepted)

import java.util.*

fun main(args: Array<String>) {
    val sc = Scanner(System.`in`)
    val n = sc.nextLong()
    println(problem114c(n))
}

fun problem114c(n: Long): Long {
    var count = 0L
    fun counter(current: Long, use: Long, used: HashSet<Long>) {
        if (current > n) return
        used.add(use)
        if (used.contains(3) && used.contains(5) && used.contains(7)) {
            count++
        }

        counter(current * 10 + 7, 7, HashSet(used))
        counter(current * 10 + 5, 5, HashSet(used))
        counter(current * 10 + 3, 3, HashSet(used))
    }

    counter(0L, 0, HashSet())
    return count
}