object Solution {
  val numbers = "0123456789".toSet
  val lower_case = "abcdefghijklmnopqrstuvwxyz".toSet
  val upper_case = "ABCDEFGHIJKLMNOPQRSTUVWXYZ".toSet
  val special_characters = "!@#$%^&*()-+".toSet
  val classes = List(numbers, lower_case, upper_case, special_characters)
  def minimumNumber(n: Int, password: String): Int =  {
    val chars = password.toSet
    val missingClasses = classes.count(_.intersect(chars).size == 0)

    Math.max(6-password.size, missingClasses)
  }

  def main(args: Array[String]) {
    val sc = new java.util.Scanner (System.in);
    var n = sc.nextInt();
    var password = sc.next();
    val answer = minimumNumber(n, password);
    println(answer)
  }
}