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