import java.util.*;
public class Main{
	public static void main(String[] args){
          Scanner sc= new Scanner(System.in);
          int n = sc.nextInt();
          int x = sc.nextInt();
          int t = sc.nextInt();
          int time = 0;
          while(n>0){
            n = n-x;
            time += t;
          }
         System.out.println(time);
  	}
} import java.util.*; util.* java public class Main{
	public static void main(String[] args){
          Scanner sc= new Scanner(System.in);
          int n = sc.nextInt();
          int x = sc.nextInt();
          int t = sc.nextInt();
          int time = 0;
          while(n>0){
            n = n-x;
            time += t;
          }
         System.out.println(time);
  	}
} Main public static void main(String[] args){
          Scanner sc= new Scanner(System.in);
          int n = sc.nextInt();
          int x = sc.nextInt();
          int t = sc.nextInt();
          int time = 0;
          while(n>0){
            n = n-x;
            time += t;
          }
         System.out.println(time);
  	} main {
          Scanner sc= new Scanner(System.in);
          int n = sc.nextInt();
          int x = sc.nextInt();
          int t = sc.nextInt();
          int time = 0;
          while(n>0){
            n = n-x;
            time += t;
          }
         System.out.println(time);
  	} Scanner sc= new Scanner(System.in); sc new Scanner(System.in) int n = sc.nextInt(); n sc.nextInt() sc.nextInt sc int x = sc.nextInt(); x sc.nextInt() sc.nextInt sc int t = sc.nextInt(); t sc.nextInt() sc.nextInt sc int time = 0; time 0 while(n>0){
            n = n-x;
            time += t;
          } n>0 n 0 {
            n = n-x;
            time += t;
          } n = n-x n n-x n x time += t time t System.out.println(time) System.out.println System.out System System.out time String[] args args public class Main{
	public static void main(String[] args){
          Scanner sc= new Scanner(System.in);
          int n = sc.nextInt();
          int x = sc.nextInt();
          int t = sc.nextInt();
          int time = 0;
          while(n>0){
            n = n-x;
            time += t;
          }
         System.out.println(time);
  	}
} public class Main{
	public static void main(String[] args){
          Scanner sc= new Scanner(System.in);
          int n = sc.nextInt();
          int x = sc.nextInt();
          int t = sc.nextInt();
          int time = 0;
          while(n>0){
            n = n-x;
            time += t;
          }
         System.out.println(time);
  	}
} Main
import java.util.*;
public class Main{
	public static void main(String[] args){
          Scanner sc= new Scanner(System.in);
          int n = sc.nextInt();
          int x = sc.nextInt();
          int t = sc.nextInt();
          int time = 0;
          while(n>0){
            n = n-x;
            time += t;
          }
         System.out.println(time);
  	}
}