import java.util.Scanner;

public class Main {

	public static void main(String[] args) {
		// TODO Auto-generated method stub
		try (Scanner sc = new Scanner(System.in)) {
           int n = sc.nextInt();
           int x = sc.nextInt();
           int t = sc.nextInt(); // minutes

           int time = 0;
           int made = 0;
           
           while (n > made ) {
        	   made += x;
        	   time += t;
           }

           System.out.println(time);

		} catch (Exception e) {
			// TODO: handle exception
		}
	}
} import java.util.Scanner; Scanner java.util public class Main {

	public static void main(String[] args) {
		// TODO Auto-generated method stub
		try (Scanner sc = new Scanner(System.in)) {
           int n = sc.nextInt();
           int x = sc.nextInt();
           int t = sc.nextInt(); // minutes

           int time = 0;
           int made = 0;
           
           while (n > made ) {
        	   made += x;
        	   time += t;
           }

           System.out.println(time);

		} catch (Exception e) {
			// TODO: handle exception
		}
	}
} Main public static void main(String[] args) {
		// TODO Auto-generated method stub
		try (Scanner sc = new Scanner(System.in)) {
           int n = sc.nextInt();
           int x = sc.nextInt();
           int t = sc.nextInt(); // minutes

           int time = 0;
           int made = 0;
           
           while (n > made ) {
        	   made += x;
        	   time += t;
           }

           System.out.println(time);

		} catch (Exception e) {
			// TODO: handle exception
		}
	} main {
		// TODO Auto-generated method stub
		try (Scanner sc = new Scanner(System.in)) {
           int n = sc.nextInt();
           int x = sc.nextInt();
           int t = sc.nextInt(); // minutes

           int time = 0;
           int made = 0;
           
           while (n > made ) {
        	   made += x;
        	   time += t;
           }

           System.out.println(time);

		} catch (Exception e) {
			// TODO: handle exception
		}
	} try (Scanner sc = new Scanner(System.in)) {
           int n = sc.nextInt();
           int x = sc.nextInt();
           int t = sc.nextInt(); // minutes

           int time = 0;
           int made = 0;
           
           while (n > made ) {
        	   made += x;
        	   time += t;
           }

           System.out.println(time);

		} catch (Exception e) {
			// TODO: handle exception
		} catch (Exception e) {
			// TODO: handle exception
		} Exception e {
			// TODO: handle exception
		} {
           int n = sc.nextInt();
           int x = sc.nextInt();
           int t = sc.nextInt(); // minutes

           int time = 0;
           int made = 0;
           
           while (n > made ) {
        	   made += x;
        	   time += t;
           }

           System.out.println(time);

		} Scanner sc = new Scanner(System.in) Scanner sc = new Scanner(System.in) 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 time = 0; time 0 int made = 0; made 0 while (n > made ) {
        	   made += x;
        	   time += t;
           } n > made n made {
        	   made += x;
        	   time += t;
           } made += x made x time += t time t System.out.println(time) System.out.println System.out System System.out time String[] args args public class Main {

	public static void main(String[] args) {
		// TODO Auto-generated method stub
		try (Scanner sc = new Scanner(System.in)) {
           int n = sc.nextInt();
           int x = sc.nextInt();
           int t = sc.nextInt(); // minutes

           int time = 0;
           int made = 0;
           
           while (n > made ) {
        	   made += x;
        	   time += t;
           }

           System.out.println(time);

		} catch (Exception e) {
			// TODO: handle exception
		}
	}
} public class Main {

	public static void main(String[] args) {
		// TODO Auto-generated method stub
		try (Scanner sc = new Scanner(System.in)) {
           int n = sc.nextInt();
           int x = sc.nextInt();
           int t = sc.nextInt(); // minutes

           int time = 0;
           int made = 0;
           
           while (n > made ) {
        	   made += x;
        	   time += t;
           }

           System.out.println(time);

		} catch (Exception e) {
			// TODO: handle exception
		}
	}
} Main
import java.util.Scanner;

public class Main {

	public static void main(String[] args) {
		// TODO Auto-generated method stub
		try (Scanner sc = new Scanner(System.in)) {
           int n = sc.nextInt();
           int x = sc.nextInt();
           int t = sc.nextInt(); // minutes

           int time = 0;
           int made = 0;
           
           while (n > made ) {
        	   made += x;
        	   time += t;
           }

           System.out.println(time);

		} catch (Exception e) {
			// TODO: handle exception
		}
	}
}
