object Main extends App {
  import io.StdIn._
  val Array(a, b) = readLine().split(" ")
  val (x, y) = (a.toLong, b.toDouble)
  val z =
    if (x * y < 1.0) 0L
  	else (x * math.round(y * 100)) / 100
  println(z)
}
