
import java.util.Scanner;

/**
 * Created by enpingkuang on 2020/9/10 10:54 下午
 */
public class Main {

    public static void main(String[] args) {
        Scanner scanner = new Scanner(System.in);
        int n = scanner.nextInt();
        int x = scanner.nextInt();
        int t = scanner.nextInt();
        int flag = n % x == 0?0:1;
        System.out.println((n/x + flag)*t);
    }
} import java.util.Scanner; Scanner java.util public class Main {

    public static void main(String[] args) {
        Scanner scanner = new Scanner(System.in);
        int n = scanner.nextInt();
        int x = scanner.nextInt();
        int t = scanner.nextInt();
        int flag = n % x == 0?0:1;
        System.out.println((n/x + flag)*t);
    }
} Main public static void main(String[] args) {
        Scanner scanner = new Scanner(System.in);
        int n = scanner.nextInt();
        int x = scanner.nextInt();
        int t = scanner.nextInt();
        int flag = n % x == 0?0:1;
        System.out.println((n/x + flag)*t);
    } main {
        Scanner scanner = new Scanner(System.in);
        int n = scanner.nextInt();
        int x = scanner.nextInt();
        int t = scanner.nextInt();
        int flag = n % x == 0?0:1;
        System.out.println((n/x + flag)*t);
    } Scanner scanner = new Scanner(System.in); scanner new Scanner(System.in) int n = scanner.nextInt(); n scanner.nextInt() scanner.nextInt scanner int x = scanner.nextInt(); x scanner.nextInt() scanner.nextInt scanner int t = scanner.nextInt(); t scanner.nextInt() scanner.nextInt scanner int flag = n % x == 0?0:1; flag n % x == 0?0:1 n % x == 0 n % x n x 0 0 1 System.out.println((n/x + flag)*t) System.out.println System.out System System.out (n/x + flag)*t (n/x + flag) n/x n x flag t String[] args args public class Main {

    public static void main(String[] args) {
        Scanner scanner = new Scanner(System.in);
        int n = scanner.nextInt();
        int x = scanner.nextInt();
        int t = scanner.nextInt();
        int flag = n % x == 0?0:1;
        System.out.println((n/x + flag)*t);
    }
} public class Main {

    public static void main(String[] args) {
        Scanner scanner = new Scanner(System.in);
        int n = scanner.nextInt();
        int x = scanner.nextInt();
        int t = scanner.nextInt();
        int flag = n % x == 0?0:1;
        System.out.println((n/x + flag)*t);
    }
} Main

import java.util.Scanner;

/**
 * Created by enpingkuang on 2020/9/10 10:54 下午
 */
public class Main {

    public static void main(String[] args) {
        Scanner scanner = new Scanner(System.in);
        int n = scanner.nextInt();
        int x = scanner.nextInt();
        int t = scanner.nextInt();
        int flag = n % x == 0?0:1;
        System.out.println((n/x + flag)*t);
    }
}
