fun main(args: Array<String>) {
    readLine()?.split(" ")?.let {
        val n = it[0].toInt()
        val x = it[1].toInt()
        val t = it[2].toInt()
        val count = (n / x) + if (n % x == 0) {
            0
        } else {
            1
        }
        val time = t * count
        println(time)
    }
}