object Main {

  def main(args: Array[String]): Unit = {
    val sc = new java.util.Scanner(System.in)
    val N = sc.nextLong()

    def solve(): Int = {
      val L = N.toString.length

      def dfs0(i: Int): Int =
        if (i < L - 3)
          dfs0(i+1) + dfs1(i+1, 0, false, false, false)
        else 0

      def dfs1(i: Int, count: Int, seven: Boolean, five: Boolean, three: Boolean): Int =
        if (i < L)
          dfs1(i+1, count + 7 * Math.pow(10, L - i - 1).toInt, true, five, three) +
          dfs1(i+1, count + 5 * Math.pow(10, L - i - 1).toInt, seven, true, three) +
          dfs1(i+1, count + 3 * Math.pow(10, L - i - 1).toInt, seven, five, true)
        else if (seven && five && three && count <= N) 1
        else 0

      val head = N.toString.head.toInt
      if (head >= 7)
        dfs1(1, 7 * Math.pow(10, L - 1).toInt, true, false, false) +
        dfs1(1, 5 * Math.pow(10, L - 1).toInt, false, true, false) +
        dfs1(1, 3 * Math.pow(10, L - 1).toInt, false, false, true) + dfs0(0)
      else if (head >= 5)
        dfs1(1, 5 * Math.pow(10, L - 1).toInt, false, true, false) +
        dfs1(1, 3 * Math.pow(10, L - 1).toInt, false, false, true) + dfs0(0)
      else if (head >= 3)
        dfs1(1, 3 * Math.pow(10, L - 1).toInt, false, false, true) + dfs0(0)
      else dfs0(0)
    }

    println(solve())
  }

}
