import java.util.*;
 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 a = 0;
      
      if(n%x > 0) a = 1;
      System.out.println(((n / x) + a )* t) ;
      
      sc.close();
      
    }
 } import java.util.*; util.* java 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 a = 0;
      
      if(n%x > 0) a = 1;
      System.out.println(((n / x) + a )* t) ;
      
      sc.close();
      
    }
 } 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 a = 0;
      
      if(n%x > 0) a = 1;
      System.out.println(((n / x) + a )* t) ;
      
      sc.close();
      
    } main {
      Scanner sc = new Scanner(System.in);
      int n = sc.nextInt();
      int x = sc.nextInt();
      int t = sc.nextInt();
      int a = 0;
      
      if(n%x > 0) a = 1;
      System.out.println(((n / x) + a )* t) ;
      
      sc.close();
      
    } 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 a = 0; a 0 if(n%x > 0) a = 1; n%x > 0 n%x n x 0 a = 1 a 1 System.out.println(((n / x) + a )* t) System.out.println System.out System System.out ((n / x) + a )* t ((n / x) + a ) (n / x) n x a t sc.close() sc.close sc String args[] args
import java.util.*;
 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 a = 0;
      
      if(n%x > 0) a = 1;
      System.out.println(((n / x) + a )* t) ;
      
      sc.close();
      
    }
 }
