
import java.util.Scanner;

public class Main {
	public static void main(String[] args) {
		Scanner scan = new Scanner(System.in);
		int count= 0;

		String L = scan.nextLine();
		String[] l = L.split(" ");

		int n = Integer.parseInt(l[0]);
		int x = Integer.parseInt(l[1]);
		int t = Integer.parseInt(l[2]);

		if(n % x == 0) {
			count = n / x;
		}else {
			count = n / x +1;
		}

		System.out.println(count * t);

		scan.close();


	}

} import java.util.Scanner; Scanner java.util public class Main {
	public static void main(String[] args) {
		Scanner scan = new Scanner(System.in);
		int count= 0;

		String L = scan.nextLine();
		String[] l = L.split(" ");

		int n = Integer.parseInt(l[0]);
		int x = Integer.parseInt(l[1]);
		int t = Integer.parseInt(l[2]);

		if(n % x == 0) {
			count = n / x;
		}else {
			count = n / x +1;
		}

		System.out.println(count * t);

		scan.close();


	}

} Main public static void main(String[] args) {
		Scanner scan = new Scanner(System.in);
		int count= 0;

		String L = scan.nextLine();
		String[] l = L.split(" ");

		int n = Integer.parseInt(l[0]);
		int x = Integer.parseInt(l[1]);
		int t = Integer.parseInt(l[2]);

		if(n % x == 0) {
			count = n / x;
		}else {
			count = n / x +1;
		}

		System.out.println(count * t);

		scan.close();


	} main {
		Scanner scan = new Scanner(System.in);
		int count= 0;

		String L = scan.nextLine();
		String[] l = L.split(" ");

		int n = Integer.parseInt(l[0]);
		int x = Integer.parseInt(l[1]);
		int t = Integer.parseInt(l[2]);

		if(n % x == 0) {
			count = n / x;
		}else {
			count = n / x +1;
		}

		System.out.println(count * t);

		scan.close();


	} Scanner scan = new Scanner(System.in); scan new Scanner(System.in) int count= 0; count 0 String L = scan.nextLine(); L scan.nextLine() scan.nextLine scan String[] l = L.split(" "); l L.split(" ") L.split L " " int n = Integer.parseInt(l[0]); n Integer.parseInt(l[0]) Integer.parseInt Integer l[0] l 0 int x = Integer.parseInt(l[1]); x Integer.parseInt(l[1]) Integer.parseInt Integer l[1] l 1 int t = Integer.parseInt(l[2]); t Integer.parseInt(l[2]) Integer.parseInt Integer l[2] l 2 if(n % x == 0) {
			count = n / x;
		}else {
			count = n / x +1;
		} n % x == 0 n % x n x 0 {
			count = n / x;
		} count = n / x count n / x n x {
			count = n / x +1;
		} count = n / x +1 count n / x +1 n / x n x 1 System.out.println(count * t) System.out.println System.out System System.out count * t count t scan.close() scan.close scan String[] args args public class Main {
	public static void main(String[] args) {
		Scanner scan = new Scanner(System.in);
		int count= 0;

		String L = scan.nextLine();
		String[] l = L.split(" ");

		int n = Integer.parseInt(l[0]);
		int x = Integer.parseInt(l[1]);
		int t = Integer.parseInt(l[2]);

		if(n % x == 0) {
			count = n / x;
		}else {
			count = n / x +1;
		}

		System.out.println(count * t);

		scan.close();


	}

} public class Main {
	public static void main(String[] args) {
		Scanner scan = new Scanner(System.in);
		int count= 0;

		String L = scan.nextLine();
		String[] l = L.split(" ");

		int n = Integer.parseInt(l[0]);
		int x = Integer.parseInt(l[1]);
		int t = Integer.parseInt(l[2]);

		if(n % x == 0) {
			count = n / x;
		}else {
			count = n / x +1;
		}

		System.out.println(count * t);

		scan.close();


	}

} Main

import java.util.Scanner;

public class Main {
	public static void main(String[] args) {
		Scanner scan = new Scanner(System.in);
		int count= 0;

		String L = scan.nextLine();
		String[] l = L.split(" ");

		int n = Integer.parseInt(l[0]);
		int x = Integer.parseInt(l[1]);
		int t = Integer.parseInt(l[2]);

		if(n % x == 0) {
			count = n / x;
		}else {
			count = n / x +1;
		}

		System.out.println(count * t);

		scan.close();


	}

}
