import java.util.Scanner;
 
public class Main {
 
	public static void main(String[] args) {
 
		Scanner sc = new Scanner(System.in);
 
		int n, x, t;
 
		n = sc.nextInt();
		x = sc.nextInt();
		t = sc.nextInt();
 
		int cook = (int) Math.ceil((double) n / (double) x);
 
		System.out.println(cook * t);
 
		sc.close();
	}
 
} import java.util.Scanner; Scanner java.util public class Main {
 
	public static void main(String[] args) {
 
		Scanner sc = new Scanner(System.in);
 
		int n, x, t;
 
		n = sc.nextInt();
		x = sc.nextInt();
		t = sc.nextInt();
 
		int cook = (int) Math.ceil((double) n / (double) x);
 
		System.out.println(cook * t);
 
		sc.close();
	}
 
} Main public static void main(String[] args) {
 
		Scanner sc = new Scanner(System.in);
 
		int n, x, t;
 
		n = sc.nextInt();
		x = sc.nextInt();
		t = sc.nextInt();
 
		int cook = (int) Math.ceil((double) n / (double) x);
 
		System.out.println(cook * t);
 
		sc.close();
	} main {
 
		Scanner sc = new Scanner(System.in);
 
		int n, x, t;
 
		n = sc.nextInt();
		x = sc.nextInt();
		t = sc.nextInt();
 
		int cook = (int) Math.ceil((double) n / (double) x);
 
		System.out.println(cook * t);
 
		sc.close();
	} Scanner sc = new Scanner(System.in); sc new Scanner(System.in) int n n x x t; t n = sc.nextInt() n sc.nextInt() sc.nextInt sc x = sc.nextInt() x sc.nextInt() sc.nextInt sc t = sc.nextInt() t sc.nextInt() sc.nextInt sc int cook = (int) Math.ceil((double) n / (double) x); cook (int) Math.ceil((double) n / (double) x) Math.ceil Math (double) n / (double) x (double) n (double) x System.out.println(cook * t) System.out.println System.out System System.out cook * t cook t sc.close() sc.close sc String[] args args public class Main {
 
	public static void main(String[] args) {
 
		Scanner sc = new Scanner(System.in);
 
		int n, x, t;
 
		n = sc.nextInt();
		x = sc.nextInt();
		t = sc.nextInt();
 
		int cook = (int) Math.ceil((double) n / (double) x);
 
		System.out.println(cook * t);
 
		sc.close();
	}
 
} public class Main {
 
	public static void main(String[] args) {
 
		Scanner sc = new Scanner(System.in);
 
		int n, x, t;
 
		n = sc.nextInt();
		x = sc.nextInt();
		t = sc.nextInt();
 
		int cook = (int) Math.ceil((double) n / (double) x);
 
		System.out.println(cook * t);
 
		sc.close();
	}
 
} Main
import java.util.Scanner;
 
public class Main {
 
	public static void main(String[] args) {
 
		Scanner sc = new Scanner(System.in);
 
		int n, x, t;
 
		n = sc.nextInt();
		x = sc.nextInt();
		t = sc.nextInt();
 
		int cook = (int) Math.ceil((double) n / (double) x);
 
		System.out.println(cook * t);
 
		sc.close();
	}
 
}