import scala.io.StdIn._
import scala.math._

object Main extends App with StdInHelper {
  val ss = readStrings
  val a = BigDecimal(ss(0).toLong)
  val b = BigDecimal(ss(1).toDouble)

  println((a * b).setScale(0, scala.math.BigDecimal.RoundingMode.FLOOR))
}

trait StdInHelper {
  def readStrings = readLine.split(" ")
  def readInts = readLine.split(" ").map(_.toInt)
  def readLongs = readLine.split(" ").map(_.toLong)
  def readDoubles = readLine.split(" ").map(_.toDouble)
}
