import java.util.Scanner;

public class Main {
  public static void main(String[] args) {
    Scanner scan = new Scanner(System.in);
    String n = scan.next();
    String x = scan.next();
    String t = scan.next();
    int nn = Integer.parseInt(n);
    int xx = Integer.parseInt(x);
    int tt = Integer.parseInt(t);
    
    int times;
    if (nn % xx == 0) {
      times = nn / xx;
    } else {
      times = (nn / xx) + 1;
    }
    int answer = tt * times;
    
    System.out.println(answer);
  }
}
/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