import java.util.Scanner;

fun main (args : Array<String>) {
  val input = Scanner(System.`in`)
    
  while (input.hasNext()) {
    val A = input.nextLong()
    val B = input.next()
    val ans = ((A * ((B[0] - '0') * 100)) + (A * B.substring(2).toLong())) / 100
    
    println(ans)
  }
}