import java.util.Scanner;

public class Main {
    public static void main(String[] args)
    {
        Scanner inputs = new Scanner(System.in);
        int n = inputs.nextInt();
        int x = inputs.nextInt();
        int t = inputs.nextInt();

        int takoyakiMade = 0;
        int timeTook = 0;
        do {
            timeTook += t;
            takoyakiMade += x;
        } while(takoyakiMade < n);
        System.out.println(timeTook);
    }
} import java.util.Scanner; Scanner java.util public class Main {
    public static void main(String[] args)
    {
        Scanner inputs = new Scanner(System.in);
        int n = inputs.nextInt();
        int x = inputs.nextInt();
        int t = inputs.nextInt();

        int takoyakiMade = 0;
        int timeTook = 0;
        do {
            timeTook += t;
            takoyakiMade += x;
        } while(takoyakiMade < n);
        System.out.println(timeTook);
    }
} Main public static void main(String[] args)
    {
        Scanner inputs = new Scanner(System.in);
        int n = inputs.nextInt();
        int x = inputs.nextInt();
        int t = inputs.nextInt();

        int takoyakiMade = 0;
        int timeTook = 0;
        do {
            timeTook += t;
            takoyakiMade += x;
        } while(takoyakiMade < n);
        System.out.println(timeTook);
    } main {
        Scanner inputs = new Scanner(System.in);
        int n = inputs.nextInt();
        int x = inputs.nextInt();
        int t = inputs.nextInt();

        int takoyakiMade = 0;
        int timeTook = 0;
        do {
            timeTook += t;
            takoyakiMade += x;
        } while(takoyakiMade < n);
        System.out.println(timeTook);
    } Scanner inputs = new Scanner(System.in); inputs new Scanner(System.in) int n = inputs.nextInt(); n inputs.nextInt() inputs.nextInt inputs int x = inputs.nextInt(); x inputs.nextInt() inputs.nextInt inputs int t = inputs.nextInt(); t inputs.nextInt() inputs.nextInt inputs int takoyakiMade = 0; takoyakiMade 0 int timeTook = 0; timeTook 0 do {
            timeTook += t;
            takoyakiMade += x;
        } while(takoyakiMade < n); takoyakiMade < n takoyakiMade n {
            timeTook += t;
            takoyakiMade += x;
        } timeTook += t timeTook t takoyakiMade += x takoyakiMade x System.out.println(timeTook) System.out.println System.out System System.out timeTook String[] args args public class Main {
    public static void main(String[] args)
    {
        Scanner inputs = new Scanner(System.in);
        int n = inputs.nextInt();
        int x = inputs.nextInt();
        int t = inputs.nextInt();

        int takoyakiMade = 0;
        int timeTook = 0;
        do {
            timeTook += t;
            takoyakiMade += x;
        } while(takoyakiMade < n);
        System.out.println(timeTook);
    }
} public class Main {
    public static void main(String[] args)
    {
        Scanner inputs = new Scanner(System.in);
        int n = inputs.nextInt();
        int x = inputs.nextInt();
        int t = inputs.nextInt();

        int takoyakiMade = 0;
        int timeTook = 0;
        do {
            timeTook += t;
            takoyakiMade += x;
        } while(takoyakiMade < n);
        System.out.println(timeTook);
    }
} Main
import java.util.Scanner;

public class Main {
    public static void main(String[] args)
    {
        Scanner inputs = new Scanner(System.in);
        int n = inputs.nextInt();
        int x = inputs.nextInt();
        int t = inputs.nextInt();

        int takoyakiMade = 0;
        int timeTook = 0;
        do {
            timeTook += t;
            takoyakiMade += x;
        } while(takoyakiMade < n);
        System.out.println(timeTook);
    }
}
