

import java.util.*;
import java.lang.*;
import java.io.*;

public class Main
{
    public static void main (String[] args)
    {
        // your code goes here
        Scanner s = new Scanner(System.in);
        int n = s.nextInt();
        int x =s.nextInt();
        int t = s.nextInt();
        int q;
        if(n%x==0)
            q = n/x;
        else
            q = n/x+1;
        System.out.println(q*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