import java.util.Scanner;

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 times = (int)Math.ceil((double)N/X);
        System.out.println(times * 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();
        int X = sc.nextInt();
        int t = sc.nextInt();

        int times = (int)Math.ceil((double)N/X);
        System.out.println(times * t);
    }
} 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 times = (int)Math.ceil((double)N/X);
        System.out.println(times * t);
    } main {
        Scanner sc = new Scanner(System.in);
        int N = sc.nextInt();
        int X = sc.nextInt();
        int t = sc.nextInt();

        int times = (int)Math.ceil((double)N/X);
        System.out.println(times * t);
    } 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 times = (int)Math.ceil((double)N/X); times (int)Math.ceil((double)N/X) Math.ceil Math (double)N/X (double)N X System.out.println(times * t) System.out.println System.out System System.out times * t times t 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 times = (int)Math.ceil((double)N/X);
        System.out.println(times * t);
    }
} 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 times = (int)Math.ceil((double)N/X);
        System.out.println(times * 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();
        int X = sc.nextInt();
        int t = sc.nextInt();

        int times = (int)Math.ceil((double)N/X);
        System.out.println(times * t);
    }
}