import java.util.*;

public class Main{
        public static void main(String[] args){

                Scanner sc = new Scanner(System.in);
                String[] input = sc.nextLine().split(" ");
                sc.close();
        int N,X,T;
        N = Integer.parseInt(input[0]);
        X = Integer.parseInt(input[1]);
        T = Integer.parseInt(input[2]);

                int result= (N / X) * T ;
        if(N%X != 0){
            result += T;
        }
        System.out.println(result);
        }
} import java.util.*; util.* java public class Main{
        public static void main(String[] args){

                Scanner sc = new Scanner(System.in);
                String[] input = sc.nextLine().split(" ");
                sc.close();
        int N,X,T;
        N = Integer.parseInt(input[0]);
        X = Integer.parseInt(input[1]);
        T = Integer.parseInt(input[2]);

                int result= (N / X) * T ;
        if(N%X != 0){
            result += T;
        }
        System.out.println(result);
        }
} Main public static void main(String[] args){

                Scanner sc = new Scanner(System.in);
                String[] input = sc.nextLine().split(" ");
                sc.close();
        int N,X,T;
        N = Integer.parseInt(input[0]);
        X = Integer.parseInt(input[1]);
        T = Integer.parseInt(input[2]);

                int result= (N / X) * T ;
        if(N%X != 0){
            result += T;
        }
        System.out.println(result);
        } main {

                Scanner sc = new Scanner(System.in);
                String[] input = sc.nextLine().split(" ");
                sc.close();
        int N,X,T;
        N = Integer.parseInt(input[0]);
        X = Integer.parseInt(input[1]);
        T = Integer.parseInt(input[2]);

                int result= (N / X) * T ;
        if(N%X != 0){
            result += T;
        }
        System.out.println(result);
        } Scanner sc = new Scanner(System.in); sc new Scanner(System.in) String[] input = sc.nextLine().split(" "); input sc.nextLine().split(" ") sc.nextLine().split sc.nextLine() sc.nextLine sc " " sc.close() sc.close sc int N N X X T; T N = Integer.parseInt(input[0]) N Integer.parseInt(input[0]) Integer.parseInt Integer input[0] input 0 X = Integer.parseInt(input[1]) X Integer.parseInt(input[1]) Integer.parseInt Integer input[1] input 1 T = Integer.parseInt(input[2]) T Integer.parseInt(input[2]) Integer.parseInt Integer input[2] input 2 int result= (N / X) * T ; result (N / X) * T (N / X) N X T if(N%X != 0){
            result += T;
        } N%X != 0 N%X N X 0 {
            result += T;
        } result += T result T System.out.println(result) System.out.println System.out System System.out result String[] args args public class Main{
        public static void main(String[] args){

                Scanner sc = new Scanner(System.in);
                String[] input = sc.nextLine().split(" ");
                sc.close();
        int N,X,T;
        N = Integer.parseInt(input[0]);
        X = Integer.parseInt(input[1]);
        T = Integer.parseInt(input[2]);

                int result= (N / X) * T ;
        if(N%X != 0){
            result += T;
        }
        System.out.println(result);
        }
} public class Main{
        public static void main(String[] args){

                Scanner sc = new Scanner(System.in);
                String[] input = sc.nextLine().split(" ");
                sc.close();
        int N,X,T;
        N = Integer.parseInt(input[0]);
        X = Integer.parseInt(input[1]);
        T = Integer.parseInt(input[2]);

                int result= (N / X) * T ;
        if(N%X != 0){
            result += T;
        }
        System.out.println(result);
        }
} Main
import java.util.*;

public class Main{
        public static void main(String[] args){

                Scanner sc = new Scanner(System.in);
                String[] input = sc.nextLine().split(" ");
                sc.close();
        int N,X,T;
        N = Integer.parseInt(input[0]);
        X = Integer.parseInt(input[1]);
        T = Integer.parseInt(input[2]);

                int result= (N / X) * T ;
        if(N%X != 0){
            result += T;
        }
        System.out.println(result);
        }
}
