import java.util.Scanner;

public class Main {
    public static void main(String[] args) {

        Scanner input = new Scanner(System.in);
        double numberOf = input.nextDouble();
        double numberAtATime = input.nextDouble();
        double timeToMake = input.nextDouble();
        double result;


        result = timeToMake * Math.ceil(numberOf / numberAtATime);
        System.out.println((int)result);

    }
}

/tmp/hf-datasets-cache/medium/datasets/42704881117311-config-parquet-and-info-qiankunmu-Project_CodeNet-896c9d36/hub/datasets--qiankunmu--Project_CodeNet_Python800_and_Java250/snapshots/c899fde44a77ba1cc14973ed3de064e4ff3aadc7/Project_CodeNet_Java250.tar.gz