import java.util.Scanner;
public class Main
{
  public static void main(String[] args)
  {
    Scanner sc = new Scanner(System.in);
    int N=sc.nextInt();
    double X=sc.nextDouble();
    int T=sc.nextInt();
    double a =N/X;
    double temp=Math.ceil(N/X);
    double ans=T*temp;
    int ans1=(int)ans;
    
    
    
    System.out.println(ans1);
  }} import java.util.Scanner; Scanner java.util public class Main
{
  public static void main(String[] args)
  {
    Scanner sc = new Scanner(System.in);
    int N=sc.nextInt();
    double X=sc.nextDouble();
    int T=sc.nextInt();
    double a =N/X;
    double temp=Math.ceil(N/X);
    double ans=T*temp;
    int ans1=(int)ans;
    
    
    
    System.out.println(ans1);
  }} Main public static void main(String[] args)
  {
    Scanner sc = new Scanner(System.in);
    int N=sc.nextInt();
    double X=sc.nextDouble();
    int T=sc.nextInt();
    double a =N/X;
    double temp=Math.ceil(N/X);
    double ans=T*temp;
    int ans1=(int)ans;
    
    
    
    System.out.println(ans1);
  } main {
    Scanner sc = new Scanner(System.in);
    int N=sc.nextInt();
    double X=sc.nextDouble();
    int T=sc.nextInt();
    double a =N/X;
    double temp=Math.ceil(N/X);
    double ans=T*temp;
    int ans1=(int)ans;
    
    
    
    System.out.println(ans1);
  } Scanner sc = new Scanner(System.in); sc new Scanner(System.in) int N=sc.nextInt(); N sc.nextInt() sc.nextInt sc double X=sc.nextDouble(); X sc.nextDouble() sc.nextDouble sc int T=sc.nextInt(); T sc.nextInt() sc.nextInt sc double a =N/X; a N/X N X double temp=Math.ceil(N/X); temp Math.ceil(N/X) Math.ceil Math N/X N X double ans=T*temp; ans T*temp T temp int ans1=(int)ans; ans1 (int)ans System.out.println(ans1) System.out.println System.out System System.out ans1 String[] args args public class Main
{
  public static void main(String[] args)
  {
    Scanner sc = new Scanner(System.in);
    int N=sc.nextInt();
    double X=sc.nextDouble();
    int T=sc.nextInt();
    double a =N/X;
    double temp=Math.ceil(N/X);
    double ans=T*temp;
    int ans1=(int)ans;
    
    
    
    System.out.println(ans1);
  }} public class Main
{
  public static void main(String[] args)
  {
    Scanner sc = new Scanner(System.in);
    int N=sc.nextInt();
    double X=sc.nextDouble();
    int T=sc.nextInt();
    double a =N/X;
    double temp=Math.ceil(N/X);
    double ans=T*temp;
    int ans1=(int)ans;
    
    
    
    System.out.println(ans1);
  }} Main
import java.util.Scanner;
public class Main
{
  public static void main(String[] args)
  {
    Scanner sc = new Scanner(System.in);
    int N=sc.nextInt();
    double X=sc.nextDouble();
    int T=sc.nextInt();
    double a =N/X;
    double temp=Math.ceil(N/X);
    double ans=T*temp;
    int ans1=(int)ans;
    
    
    
    System.out.println(ans1);
  }}