import java.util.Scanner;

public class Main {

	public static void main(String[] args) {
		try(Scanner scanner = new Scanner(System.in)) {
			String data = scanner.nextLine();

			String[] arr = data.split(" ");
			int n = Integer.parseInt(arr[0]);
			int x = Integer.parseInt(arr[1]);
			int t = Integer.parseInt(arr[2]);

			int index = 0;
			int res = n;
			while(res > 0) {
				res = res - x;
				index++;
			}

			System.out.println(index * t);
		}
	}
} import java.util.Scanner; Scanner java.util public class Main {

	public static void main(String[] args) {
		try(Scanner scanner = new Scanner(System.in)) {
			String data = scanner.nextLine();

			String[] arr = data.split(" ");
			int n = Integer.parseInt(arr[0]);
			int x = Integer.parseInt(arr[1]);
			int t = Integer.parseInt(arr[2]);

			int index = 0;
			int res = n;
			while(res > 0) {
				res = res - x;
				index++;
			}

			System.out.println(index * t);
		}
	}
} Main public static void main(String[] args) {
		try(Scanner scanner = new Scanner(System.in)) {
			String data = scanner.nextLine();

			String[] arr = data.split(" ");
			int n = Integer.parseInt(arr[0]);
			int x = Integer.parseInt(arr[1]);
			int t = Integer.parseInt(arr[2]);

			int index = 0;
			int res = n;
			while(res > 0) {
				res = res - x;
				index++;
			}

			System.out.println(index * t);
		}
	} main {
		try(Scanner scanner = new Scanner(System.in)) {
			String data = scanner.nextLine();

			String[] arr = data.split(" ");
			int n = Integer.parseInt(arr[0]);
			int x = Integer.parseInt(arr[1]);
			int t = Integer.parseInt(arr[2]);

			int index = 0;
			int res = n;
			while(res > 0) {
				res = res - x;
				index++;
			}

			System.out.println(index * t);
		}
	} try(Scanner scanner = new Scanner(System.in)) {
			String data = scanner.nextLine();

			String[] arr = data.split(" ");
			int n = Integer.parseInt(arr[0]);
			int x = Integer.parseInt(arr[1]);
			int t = Integer.parseInt(arr[2]);

			int index = 0;
			int res = n;
			while(res > 0) {
				res = res - x;
				index++;
			}

			System.out.println(index * t);
		} {
			String data = scanner.nextLine();

			String[] arr = data.split(" ");
			int n = Integer.parseInt(arr[0]);
			int x = Integer.parseInt(arr[1]);
			int t = Integer.parseInt(arr[2]);

			int index = 0;
			int res = n;
			while(res > 0) {
				res = res - x;
				index++;
			}

			System.out.println(index * t);
		} Scanner scanner = new Scanner(System.in) Scanner scanner = new Scanner(System.in) new Scanner(System.in) String data = scanner.nextLine(); data scanner.nextLine() scanner.nextLine scanner String[] arr = data.split(" "); arr data.split(" ") data.split data " " int n = Integer.parseInt(arr[0]); n Integer.parseInt(arr[0]) Integer.parseInt Integer arr[0] arr 0 int x = Integer.parseInt(arr[1]); x Integer.parseInt(arr[1]) Integer.parseInt Integer arr[1] arr 1 int t = Integer.parseInt(arr[2]); t Integer.parseInt(arr[2]) Integer.parseInt Integer arr[2] arr 2 int index = 0; index 0 int res = n; res n while(res > 0) {
				res = res - x;
				index++;
			} res > 0 res 0 {
				res = res - x;
				index++;
			} res = res - x res res - x res x index++ index System.out.println(index * t) System.out.println System.out System System.out index * t index t String[] args args public class Main {

	public static void main(String[] args) {
		try(Scanner scanner = new Scanner(System.in)) {
			String data = scanner.nextLine();

			String[] arr = data.split(" ");
			int n = Integer.parseInt(arr[0]);
			int x = Integer.parseInt(arr[1]);
			int t = Integer.parseInt(arr[2]);

			int index = 0;
			int res = n;
			while(res > 0) {
				res = res - x;
				index++;
			}

			System.out.println(index * t);
		}
	}
} public class Main {

	public static void main(String[] args) {
		try(Scanner scanner = new Scanner(System.in)) {
			String data = scanner.nextLine();

			String[] arr = data.split(" ");
			int n = Integer.parseInt(arr[0]);
			int x = Integer.parseInt(arr[1]);
			int t = Integer.parseInt(arr[2]);

			int index = 0;
			int res = n;
			while(res > 0) {
				res = res - x;
				index++;
			}

			System.out.println(index * t);
		}
	}
} Main
import java.util.Scanner;

public class Main {

	public static void main(String[] args) {
		try(Scanner scanner = new Scanner(System.in)) {
			String data = scanner.nextLine();

			String[] arr = data.split(" ");
			int n = Integer.parseInt(arr[0]);
			int x = Integer.parseInt(arr[1]);
			int t = Integer.parseInt(arr[2]);

			int index = 0;
			int res = n;
			while(res > 0) {
				res = res - x;
				index++;
			}

			System.out.println(index * t);
		}
	}
}
