object Main{
  def main(args: Array[String]){
    val input=io.Source.stdin.getLines().mkString("\n")
    println(solve(input).trim())
  }

  def solve(input:String):String={
    val Array(a,b) = input.split(" ").map(_.toInt)
    (50*a + (500*a/(8+2*b))).toString
  }
}