import java.util.*;
import java.lang.*;
class Main
{
public static void main(String args[])
{
    Scanner obj=new Scanner(System.in);
    int n,x,t;double c=0;
    n=obj.nextInt();
    x=obj.nextInt();
    t=obj.nextInt();
  	double m=n;
    c=t*Math.ceil(m/x);
    System.out.println((int)c);
}
}
/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