import java.util.Scanner;

public class Main {
    public static void main(String... args) {
        Scanner scanner = new Scanner(System.in);

        double N = scanner.nextInt();
        double X = scanner.nextInt();
        int T = scanner.nextInt();

        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 scanner = new Scanner(System.in);

        double N = scanner.nextInt();
        double X = scanner.nextInt();
        int T = scanner.nextInt();

        System.out.println((int) Math.ceil(N/X) * T);
    }
} Main public static void main(String... args) {
        Scanner scanner = new Scanner(System.in);

        double N = scanner.nextInt();
        double X = scanner.nextInt();
        int T = scanner.nextInt();

        System.out.println((int) Math.ceil(N/X) * T);
    } main {
        Scanner scanner = new Scanner(System.in);

        double N = scanner.nextInt();
        double X = scanner.nextInt();
        int T = scanner.nextInt();

        System.out.println((int) Math.ceil(N/X) * T);
    } Scanner scanner = new Scanner(System.in); scanner new Scanner(System.in) double N = scanner.nextInt(); N scanner.nextInt() scanner.nextInt scanner double X = scanner.nextInt(); X scanner.nextInt() scanner.nextInt scanner int T = scanner.nextInt(); T scanner.nextInt() scanner.nextInt scanner System.out.println((int) Math.ceil(N/X) * T) System.out.println System.out System System.out (int) Math.ceil(N/X) * T (int) 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 scanner = new Scanner(System.in);

        double N = scanner.nextInt();
        double X = scanner.nextInt();
        int T = scanner.nextInt();

        System.out.println((int) Math.ceil(N/X) * T);
    }
} public class Main {
    public static void main(String... args) {
        Scanner scanner = new Scanner(System.in);

        double N = scanner.nextInt();
        double X = scanner.nextInt();
        int T = scanner.nextInt();

        System.out.println((int) Math.ceil(N/X) * T);
    }
} Main
import java.util.Scanner;

public class Main {
    public static void main(String... args) {
        Scanner scanner = new Scanner(System.in);

        double N = scanner.nextInt();
        double X = scanner.nextInt();
        int T = scanner.nextInt();

        System.out.println((int) Math.ceil(N/X) * T);
    }
}
