import java.util.List;
import java.util.ArrayList;
import java.util.Collections;
import java.util.Scanner;
public class Main {
	public static void main(String[] args) {
        Scanner sn = new Scanner(System.in);
        int  n = Integer.parseInt(sn.next());
        int  x = Integer.parseInt(sn.next());
        int  t = Integer.parseInt(sn.next());
        int c = n % x;
      if (c > 0){
        System.out.println((n / x + 1)* t);
      } else {
         System.out.println((n / x )* t);
      }
   }
} import java.util.List; List java.util import java.util.ArrayList; ArrayList java.util import java.util.Collections; Collections java.util import java.util.Scanner; Scanner java.util public class Main {
	public static void main(String[] args) {
        Scanner sn = new Scanner(System.in);
        int  n = Integer.parseInt(sn.next());
        int  x = Integer.parseInt(sn.next());
        int  t = Integer.parseInt(sn.next());
        int c = n % x;
      if (c > 0){
        System.out.println((n / x + 1)* t);
      } else {
         System.out.println((n / x )* t);
      }
   }
} Main public static void main(String[] args) {
        Scanner sn = new Scanner(System.in);
        int  n = Integer.parseInt(sn.next());
        int  x = Integer.parseInt(sn.next());
        int  t = Integer.parseInt(sn.next());
        int c = n % x;
      if (c > 0){
        System.out.println((n / x + 1)* t);
      } else {
         System.out.println((n / x )* t);
      }
   } main {
        Scanner sn = new Scanner(System.in);
        int  n = Integer.parseInt(sn.next());
        int  x = Integer.parseInt(sn.next());
        int  t = Integer.parseInt(sn.next());
        int c = n % x;
      if (c > 0){
        System.out.println((n / x + 1)* t);
      } else {
         System.out.println((n / x )* t);
      }
   } Scanner sn = new Scanner(System.in); sn new Scanner(System.in) int  n = Integer.parseInt(sn.next()); n Integer.parseInt(sn.next()) Integer.parseInt Integer sn.next() sn.next sn int  x = Integer.parseInt(sn.next()); x Integer.parseInt(sn.next()) Integer.parseInt Integer sn.next() sn.next sn int  t = Integer.parseInt(sn.next()); t Integer.parseInt(sn.next()) Integer.parseInt Integer sn.next() sn.next sn int c = n % x; c n % x n x if (c > 0){
        System.out.println((n / x + 1)* t);
      } else {
         System.out.println((n / x )* t);
      } c > 0 c 0 {
        System.out.println((n / x + 1)* t);
      } System.out.println((n / x + 1)* t) System.out.println System.out System System.out (n / x + 1)* t (n / x + 1) n / x n x 1 t {
         System.out.println((n / x )* t);
      } System.out.println((n / x )* t) System.out.println System.out System System.out (n / x )* t (n / x ) n x t String[] args args public class Main {
	public static void main(String[] args) {
        Scanner sn = new Scanner(System.in);
        int  n = Integer.parseInt(sn.next());
        int  x = Integer.parseInt(sn.next());
        int  t = Integer.parseInt(sn.next());
        int c = n % x;
      if (c > 0){
        System.out.println((n / x + 1)* t);
      } else {
         System.out.println((n / x )* t);
      }
   }
} public class Main {
	public static void main(String[] args) {
        Scanner sn = new Scanner(System.in);
        int  n = Integer.parseInt(sn.next());
        int  x = Integer.parseInt(sn.next());
        int  t = Integer.parseInt(sn.next());
        int c = n % x;
      if (c > 0){
        System.out.println((n / x + 1)* t);
      } else {
         System.out.println((n / x )* t);
      }
   }
} Main
import java.util.List;
import java.util.ArrayList;
import java.util.Collections;
import java.util.Scanner;
public class Main {
	public static void main(String[] args) {
        Scanner sn = new Scanner(System.in);
        int  n = Integer.parseInt(sn.next());
        int  x = Integer.parseInt(sn.next());
        int  t = Integer.parseInt(sn.next());
        int c = n % x;
      if (c > 0){
        System.out.println((n / x + 1)* t);
      } else {
         System.out.println((n / x )* t);
      }
   }
}
