//package basics.AtCoders;

import java.util.Scanner;

public class Main {
    public static void main(String[] args) {
        Scanner s =new Scanner(System.in);
        int N = s.nextInt(); //how many pieces made in time
        int X = s.nextInt(); // pieces given
        int T = s.nextInt(); // time
        if(N%X==0){
            System.out.println(N/X*T);
        }
        else {
            System.out.println((N/X+1)*T);
        }


    }
}

/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