import java.util.Scanner;

public class Main {
	public static void main(String args[]) {
		Scanner sc = new Scanner(System.in);
		int N = sc.nextInt();
		int X = sc.nextInt();
		int T = sc.nextInt();

		int A = 0;

		if (N%X >0) A = 1;

		System.out.println((N/X + A) * T);
		sc.close();
	}
} import java.util.Scanner; Scanner java.util public class Main {
	public static void main(String args[]) {
		Scanner sc = new Scanner(System.in);
		int N = sc.nextInt();
		int X = sc.nextInt();
		int T = sc.nextInt();

		int A = 0;

		if (N%X >0) A = 1;

		System.out.println((N/X + A) * T);
		sc.close();
	}
} Main public static void main(String args[]) {
		Scanner sc = new Scanner(System.in);
		int N = sc.nextInt();
		int X = sc.nextInt();
		int T = sc.nextInt();

		int A = 0;

		if (N%X >0) A = 1;

		System.out.println((N/X + A) * T);
		sc.close();
	} main {
		Scanner sc = new Scanner(System.in);
		int N = sc.nextInt();
		int X = sc.nextInt();
		int T = sc.nextInt();

		int A = 0;

		if (N%X >0) A = 1;

		System.out.println((N/X + A) * T);
		sc.close();
	} Scanner sc = new Scanner(System.in); sc 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 A = 0; A 0 if (N%X >0) A = 1; N%X >0 N%X N X 0 A = 1 A 1 System.out.println((N/X + A) * T) System.out.println System.out System System.out (N/X + A) * T (N/X + A) N/X N X A T sc.close() sc.close sc String args[] args public class Main {
	public static void main(String args[]) {
		Scanner sc = new Scanner(System.in);
		int N = sc.nextInt();
		int X = sc.nextInt();
		int T = sc.nextInt();

		int A = 0;

		if (N%X >0) A = 1;

		System.out.println((N/X + A) * T);
		sc.close();
	}
} public class Main {
	public static void main(String args[]) {
		Scanner sc = new Scanner(System.in);
		int N = sc.nextInt();
		int X = sc.nextInt();
		int T = sc.nextInt();

		int A = 0;

		if (N%X >0) A = 1;

		System.out.println((N/X + A) * T);
		sc.close();
	}
} Main
import java.util.Scanner;

public class Main {
	public static void main(String args[]) {
		Scanner sc = new Scanner(System.in);
		int N = sc.nextInt();
		int X = sc.nextInt();
		int T = sc.nextInt();

		int A = 0;

		if (N%X >0) A = 1;

		System.out.println((N/X + A) * T);
		sc.close();
	}
}
