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 Scala (2.11.7) (judge verdict: Accepted)

import java.util.Scanner

import scala.collection.mutable.ArrayBuffer

object Main extends App {
  val sc = new Scanner(System.in)

  def taskA() = {
    val ans = sc.nextInt() match {
      case 7 | 5 | 3 => "YES"
      case _ => "NO"
    }
    println(ans)
  }

  def taskB() = {
    val s = sc.next()
    val n = s.length
    val ans = 0.until(n - 2).fold(10000) { (acc, x) =>
      val y = s.substring(x, x + 3).toInt
      Math.min(acc, Math.abs(y - 753))
    }
    println(ans)
  }

  def taskC() = {
    val s = sc.next()
    val n = s.toInt

    def rec(pos: Int, l: Int, ab: ArrayBuffer[Int]): Int = {
      if (pos == l) {
        val ok = Seq(7, 5, 3).forall(ab.contains(_)) && ab.mkString.toInt <= n
        if (ok) 1 else 0
      } else {
        Seq(7, 5, 3).map { i =>
          ab(pos) = i
          rec(pos + 1, l, ab)
        }.sum
      }
    }

    val l = s.length

    val ans = 3.to(l).map { i =>
      val ab = ArrayBuffer.fill(i)(0)
      rec(0, i, ab)
    }.sum
    println(ans)
  }


  taskC()
}