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 ans = 0;
        int times = 0 ;
        times = (int) Math.ceil((double) N / X);

        ans = times * T;

        System.out.println(ans);

    }
} 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 ans = 0;
        int times = 0 ;
        times = (int) Math.ceil((double) N / X);

        ans = times * T;

        System.out.println(ans);

    }
} 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 ans = 0;
        int times = 0 ;
        times = (int) Math.ceil((double) N / X);

        ans = times * T;

        System.out.println(ans);

    } main {
        Scanner sc = new Scanner(System.in);
        int N = sc.nextInt();
        int X = sc.nextInt();
        int T = sc.nextInt();

        int ans = 0;
        int times = 0 ;
        times = (int) Math.ceil((double) N / X);

        ans = times * T;

        System.out.println(ans);

    } 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 ans = 0; ans 0 int times = 0 ; times 0 times = (int) Math.ceil((double) N / X) times (int) Math.ceil((double) N / X) Math.ceil Math (double) N / X (double) N X ans = times * T ans times * T times T System.out.println(ans) System.out.println System.out System System.out ans 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 ans = 0;
        int times = 0 ;
        times = (int) Math.ceil((double) N / X);

        ans = times * T;

        System.out.println(ans);

    }
} 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 ans = 0;
        int times = 0 ;
        times = (int) Math.ceil((double) N / X);

        ans = times * T;

        System.out.println(ans);

    }
} 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 ans = 0;
        int times = 0 ;
        times = (int) Math.ceil((double) N / X);

        ans = times * T;

        System.out.println(ans);

    }
}