import java.util.Scanner;
 
public class Main {
 
    public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
		int n = sc.nextInt();//目標
      	double x = sc.nextDouble();//一回あたり
      	double t = sc.nextDouble();//時間
   
    	System.out.println((int)(Math.ceil(n/x)*t));
    } 
}
















 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();//目標
      	double x = sc.nextDouble();//一回あたり
      	double t = sc.nextDouble();//時間
   
    	System.out.println((int)(Math.ceil(n/x)*t));
    } 
} Main public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
		int n = sc.nextInt();//目標
      	double x = sc.nextDouble();//一回あたり
      	double t = sc.nextDouble();//時間
   
    	System.out.println((int)(Math.ceil(n/x)*t));
    } main {
		Scanner sc = new Scanner(System.in);
		int n = sc.nextInt();//目標
      	double x = sc.nextDouble();//一回あたり
      	double t = sc.nextDouble();//時間
   
    	System.out.println((int)(Math.ceil(n/x)*t));
    } 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 double t = sc.nextDouble(); t sc.nextDouble() sc.nextDouble sc System.out.println((int)(Math.ceil(n/x)*t)) System.out.println System.out System System.out (int)(Math.ceil(n/x)*t) Math.ceil(n/x) Math.ceil Math n/x n x t String[] args args public class Main {
 
    public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
		int n = sc.nextInt();//目標
      	double x = sc.nextDouble();//一回あたり
      	double t = sc.nextDouble();//時間
   
    	System.out.println((int)(Math.ceil(n/x)*t));
    } 
} public class Main {
 
    public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
		int n = sc.nextInt();//目標
      	double x = sc.nextDouble();//一回あたり
      	double t = sc.nextDouble();//時間
   
    	System.out.println((int)(Math.ceil(n/x)*t));
    } 
} Main
import java.util.Scanner;
 
public class Main {
 
    public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
		int n = sc.nextInt();//目標
      	double x = sc.nextDouble();//一回あたり
      	double t = sc.nextDouble();//時間
   
    	System.out.println((int)(Math.ceil(n/x)*t));
    } 
}

















