import java.util.*

private fun readLn() = readLine()!! // string line
private fun readInt() = readLn().toInt() // single int
private fun readStrings() = readLn().split(" ") // list of strings
private fun readInts() = readStrings().map { it.toInt() } // list of ints

private fun readDouble() = readLn().toDouble()
private fun readDoubles() = readStrings().map { it.toDouble() }

fun main(){

    val scanner = Scanner(System.`in`)

    val a = scanner.next().toBigDecimal()
    val b = scanner.next().toBigDecimal()
    println((a*b).toBigInteger())
}

