import scala.io.{StdIn => in}
import scala.collection.{mutable => mu}

object Main extends App {
  val s = in.readLine
  val digit = s.size
  val N = s.toInt

  def dfsEnum(d:Int, n:Int):Int = {
    // d進 n個列挙
    val enum = Array.ofDim[Int](n)
    var ret = 0
    var terms = true //仮変数 実装時置き換える
  
    def evalute():Unit = {
      if(!n753.indices.forall(i => enum.exists(_ == n753(i)))) return
      val num = enum.mkString.toInt
      if(num <= N) {
        ret += 1
        // println(num)
      }
    }
  
    def dfs(cnt:Int):Unit = {
      if(cnt == n) evalute
      else {
        for(i <- n753) {
          enum(cnt) = i
          dfs(cnt+1)
        }
      }
    }
  
    dfs(0)
    ret
  }

  val n753 = Array(3,5,7)
  val ans = (3 to digit).map(i => dfsEnum(n753.size, i)).sum
  println(ans)
}