import java.util.Map.Entry;
import java.util.*;
 
//import org.w3c.dom.css.Counter;
 
public class Main {
//public class App {
 
    public static void main(final String[] args){
     //スキャン
     final Scanner s = new Scanner(System.in);
      int N = Integer.parseInt(s.next());
      int X = Integer.parseInt(s.next());
      int T = Integer.parseInt(s.next());
      int ans = N /X;
      if(N%X !=0){ans ++;}
      System.out.println(ans*T);
    }
} import java.util.Map.Entry; Entry java.util.Map import java.util.*; util.* java public class Main {
//public class App {
 
    public static void main(final String[] args){
     //スキャン
     final Scanner s = new Scanner(System.in);
      int N = Integer.parseInt(s.next());
      int X = Integer.parseInt(s.next());
      int T = Integer.parseInt(s.next());
      int ans = N /X;
      if(N%X !=0){ans ++;}
      System.out.println(ans*T);
    }
} Main public static void main(final String[] args){
     //スキャン
     final Scanner s = new Scanner(System.in);
      int N = Integer.parseInt(s.next());
      int X = Integer.parseInt(s.next());
      int T = Integer.parseInt(s.next());
      int ans = N /X;
      if(N%X !=0){ans ++;}
      System.out.println(ans*T);
    } main {
     //スキャン
     final Scanner s = new Scanner(System.in);
      int N = Integer.parseInt(s.next());
      int X = Integer.parseInt(s.next());
      int T = Integer.parseInt(s.next());
      int ans = N /X;
      if(N%X !=0){ans ++;}
      System.out.println(ans*T);
    } final Scanner s = new Scanner(System.in); s new Scanner(System.in) int N = Integer.parseInt(s.next()); N Integer.parseInt(s.next()) Integer.parseInt Integer s.next() s.next s int X = Integer.parseInt(s.next()); X Integer.parseInt(s.next()) Integer.parseInt Integer s.next() s.next s int T = Integer.parseInt(s.next()); T Integer.parseInt(s.next()) Integer.parseInt Integer s.next() s.next s int ans = N /X; ans N /X N X if(N%X !=0){ans ++;} N%X !=0 N%X N X 0 {ans ++;} ans ++ ans System.out.println(ans*T) System.out.println System.out System System.out ans*T ans T final String[] args args public class Main {
//public class App {
 
    public static void main(final String[] args){
     //スキャン
     final Scanner s = new Scanner(System.in);
      int N = Integer.parseInt(s.next());
      int X = Integer.parseInt(s.next());
      int T = Integer.parseInt(s.next());
      int ans = N /X;
      if(N%X !=0){ans ++;}
      System.out.println(ans*T);
    }
} public class Main {
//public class App {
 
    public static void main(final String[] args){
     //スキャン
     final Scanner s = new Scanner(System.in);
      int N = Integer.parseInt(s.next());
      int X = Integer.parseInt(s.next());
      int T = Integer.parseInt(s.next());
      int ans = N /X;
      if(N%X !=0){ans ++;}
      System.out.println(ans*T);
    }
} Main
import java.util.Map.Entry;
import java.util.*;
 
//import org.w3c.dom.css.Counter;
 
public class Main {
//public class App {
 
    public static void main(final String[] args){
     //スキャン
     final Scanner s = new Scanner(System.in);
      int N = Integer.parseInt(s.next());
      int X = Integer.parseInt(s.next());
      int T = Integer.parseInt(s.next());
      int ans = N /X;
      if(N%X !=0){ans ++;}
      System.out.println(ans*T);
    }
}
