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 tmps = n / x;
        int tmpa = n % x;
        if (tmpa == 0) {
            System.out.println(tmps * t);
        } else {
            System.out.println((tmps + 1) * 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 tmps = n / x;
        int tmpa = n % x;
        if (tmpa == 0) {
            System.out.println(tmps * t);
        } else {
            System.out.println((tmps + 1) * 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 tmps = n / x;
        int tmpa = n % x;
        if (tmpa == 0) {
            System.out.println(tmps * t);
        } else {
            System.out.println((tmps + 1) * t);
        }
    } main {
        Scanner sc = new Scanner(System.in);
        int n = sc.nextInt();
        int x = sc.nextInt();
        int t = sc.nextInt();
        int tmps = n / x;
        int tmpa = n % x;
        if (tmpa == 0) {
            System.out.println(tmps * t);
        } else {
            System.out.println((tmps + 1) * 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 tmps = n / x; tmps n / x n x int tmpa = n % x; tmpa n % x n x if (tmpa == 0) {
            System.out.println(tmps * t);
        } else {
            System.out.println((tmps + 1) * t);
        } tmpa == 0 tmpa 0 {
            System.out.println(tmps * t);
        } System.out.println(tmps * t) System.out.println System.out System System.out tmps * t tmps t {
            System.out.println((tmps + 1) * t);
        } System.out.println((tmps + 1) * t) System.out.println System.out System System.out (tmps + 1) * t (tmps + 1) tmps 1 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 tmps = n / x;
        int tmpa = n % x;
        if (tmpa == 0) {
            System.out.println(tmps * t);
        } else {
            System.out.println((tmps + 1) * 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 tmps = n / x;
        int tmpa = n % x;
        if (tmpa == 0) {
            System.out.println(tmps * t);
        } else {
            System.out.println((tmps + 1) * 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 tmps = n / x;
        int tmpa = n % x;
        if (tmpa == 0) {
            System.out.println(tmps * t);
        } else {
            System.out.println((tmps + 1) * t);
        }
    }
}
