import java.util.Scanner;

public class Main {

	static int solve(int n, int x, int t) {

		int minute;
		if (n % x == 0)
			minute = (n / x) * t;
		else
			minute = (n / x + 1) * t;

		return minute;
	}

	public static void main(String[] args) {
		Scanner stdIn = new Scanner(System.in);
		int n, x, t;

		n = stdIn.nextInt();
		x = stdIn.nextInt();
		t = stdIn.nextInt();

		int result = solve(n, x, t);
		System.out.println(result);

		stdIn.close();
	}
} import java.util.Scanner; Scanner java.util public class Main {

	static int solve(int n, int x, int t) {

		int minute;
		if (n % x == 0)
			minute = (n / x) * t;
		else
			minute = (n / x + 1) * t;

		return minute;
	}

	public static void main(String[] args) {
		Scanner stdIn = new Scanner(System.in);
		int n, x, t;

		n = stdIn.nextInt();
		x = stdIn.nextInt();
		t = stdIn.nextInt();

		int result = solve(n, x, t);
		System.out.println(result);

		stdIn.close();
	}
} Main static int solve(int n, int x, int t) {

		int minute;
		if (n % x == 0)
			minute = (n / x) * t;
		else
			minute = (n / x + 1) * t;

		return minute;
	} solve {

		int minute;
		if (n % x == 0)
			minute = (n / x) * t;
		else
			minute = (n / x + 1) * t;

		return minute;
	} int minute; minute if (n % x == 0)
			minute = (n / x) * t;
		else
			minute = (n / x + 1) * t; n % x == 0 n % x n x 0 minute = (n / x) * t minute (n / x) * t (n / x) n x t minute = (n / x + 1) * t minute (n / x + 1) * t (n / x + 1) n / x n x 1 t return minute; minute int n n int x x int t t public static void main(String[] args) {
		Scanner stdIn = new Scanner(System.in);
		int n, x, t;

		n = stdIn.nextInt();
		x = stdIn.nextInt();
		t = stdIn.nextInt();

		int result = solve(n, x, t);
		System.out.println(result);

		stdIn.close();
	} main {
		Scanner stdIn = new Scanner(System.in);
		int n, x, t;

		n = stdIn.nextInt();
		x = stdIn.nextInt();
		t = stdIn.nextInt();

		int result = solve(n, x, t);
		System.out.println(result);

		stdIn.close();
	} Scanner stdIn = new Scanner(System.in); stdIn new Scanner(System.in) int n n x x t; t n = stdIn.nextInt() n stdIn.nextInt() stdIn.nextInt stdIn x = stdIn.nextInt() x stdIn.nextInt() stdIn.nextInt stdIn t = stdIn.nextInt() t stdIn.nextInt() stdIn.nextInt stdIn int result = solve(n, x, t); result solve(n, x, t) solve n x t System.out.println(result) System.out.println System.out System System.out result stdIn.close() stdIn.close stdIn String[] args args public class Main {

	static int solve(int n, int x, int t) {

		int minute;
		if (n % x == 0)
			minute = (n / x) * t;
		else
			minute = (n / x + 1) * t;

		return minute;
	}

	public static void main(String[] args) {
		Scanner stdIn = new Scanner(System.in);
		int n, x, t;

		n = stdIn.nextInt();
		x = stdIn.nextInt();
		t = stdIn.nextInt();

		int result = solve(n, x, t);
		System.out.println(result);

		stdIn.close();
	}
} public class Main {

	static int solve(int n, int x, int t) {

		int minute;
		if (n % x == 0)
			minute = (n / x) * t;
		else
			minute = (n / x + 1) * t;

		return minute;
	}

	public static void main(String[] args) {
		Scanner stdIn = new Scanner(System.in);
		int n, x, t;

		n = stdIn.nextInt();
		x = stdIn.nextInt();
		t = stdIn.nextInt();

		int result = solve(n, x, t);
		System.out.println(result);

		stdIn.close();
	}
} Main
import java.util.Scanner;

public class Main {

	static int solve(int n, int x, int t) {

		int minute;
		if (n % x == 0)
			minute = (n / x) * t;
		else
			minute = (n / x + 1) * t;

		return minute;
	}

	public static void main(String[] args) {
		Scanner stdIn = new Scanner(System.in);
		int n, x, t;

		n = stdIn.nextInt();
		x = stdIn.nextInt();
		t = stdIn.nextInt();

		int result = solve(n, x, t);
		System.out.println(result);

		stdIn.close();
	}
}
