import java.util.Scanner;

public class Main {

	public static void main(String[] args) {
		// TODO 自動生成されたメソッド・スタブ
		Scanner scannerS = new Scanner(System.in);
		int N = scannerS.nextInt();
		int X = scannerS.nextInt();
		int T = scannerS.nextInt();

		int a = 0;
		int b = N % X;
		int c = N / X;

		if (b == 0) {
			a = (N / X) * T;
		} else if (b != 0) {
			a = (c + 1) * T;
		}

		System.out.println(a);

	}

} import java.util.Scanner; Scanner java.util public class Main {

	public static void main(String[] args) {
		// TODO 自動生成されたメソッド・スタブ
		Scanner scannerS = new Scanner(System.in);
		int N = scannerS.nextInt();
		int X = scannerS.nextInt();
		int T = scannerS.nextInt();

		int a = 0;
		int b = N % X;
		int c = N / X;

		if (b == 0) {
			a = (N / X) * T;
		} else if (b != 0) {
			a = (c + 1) * T;
		}

		System.out.println(a);

	}

} Main public static void main(String[] args) {
		// TODO 自動生成されたメソッド・スタブ
		Scanner scannerS = new Scanner(System.in);
		int N = scannerS.nextInt();
		int X = scannerS.nextInt();
		int T = scannerS.nextInt();

		int a = 0;
		int b = N % X;
		int c = N / X;

		if (b == 0) {
			a = (N / X) * T;
		} else if (b != 0) {
			a = (c + 1) * T;
		}

		System.out.println(a);

	} main {
		// TODO 自動生成されたメソッド・スタブ
		Scanner scannerS = new Scanner(System.in);
		int N = scannerS.nextInt();
		int X = scannerS.nextInt();
		int T = scannerS.nextInt();

		int a = 0;
		int b = N % X;
		int c = N / X;

		if (b == 0) {
			a = (N / X) * T;
		} else if (b != 0) {
			a = (c + 1) * T;
		}

		System.out.println(a);

	} Scanner scannerS = new Scanner(System.in); scannerS new Scanner(System.in) int N = scannerS.nextInt(); N scannerS.nextInt() scannerS.nextInt scannerS int X = scannerS.nextInt(); X scannerS.nextInt() scannerS.nextInt scannerS int T = scannerS.nextInt(); T scannerS.nextInt() scannerS.nextInt scannerS int a = 0; a 0 int b = N % X; b N % X N X int c = N / X; c N / X N X if (b == 0) {
			a = (N / X) * T;
		} else if (b != 0) {
			a = (c + 1) * T;
		} b == 0 b 0 {
			a = (N / X) * T;
		} a = (N / X) * T a (N / X) * T (N / X) N X T if (b != 0) {
			a = (c + 1) * T;
		} b != 0 b 0 {
			a = (c + 1) * T;
		} a = (c + 1) * T a (c + 1) * T (c + 1) c 1 T System.out.println(a) System.out.println System.out System System.out a String[] args args public class Main {

	public static void main(String[] args) {
		// TODO 自動生成されたメソッド・スタブ
		Scanner scannerS = new Scanner(System.in);
		int N = scannerS.nextInt();
		int X = scannerS.nextInt();
		int T = scannerS.nextInt();

		int a = 0;
		int b = N % X;
		int c = N / X;

		if (b == 0) {
			a = (N / X) * T;
		} else if (b != 0) {
			a = (c + 1) * T;
		}

		System.out.println(a);

	}

} public class Main {

	public static void main(String[] args) {
		// TODO 自動生成されたメソッド・スタブ
		Scanner scannerS = new Scanner(System.in);
		int N = scannerS.nextInt();
		int X = scannerS.nextInt();
		int T = scannerS.nextInt();

		int a = 0;
		int b = N % X;
		int c = N / X;

		if (b == 0) {
			a = (N / X) * T;
		} else if (b != 0) {
			a = (c + 1) * T;
		}

		System.out.println(a);

	}

} Main
import java.util.Scanner;

public class Main {

	public static void main(String[] args) {
		// TODO 自動生成されたメソッド・スタブ
		Scanner scannerS = new Scanner(System.in);
		int N = scannerS.nextInt();
		int X = scannerS.nextInt();
		int T = scannerS.nextInt();

		int a = 0;
		int b = N % X;
		int c = N / X;

		if (b == 0) {
			a = (N / X) * T;
		} else if (b != 0) {
			a = (c + 1) * T;
		}

		System.out.println(a);

	}

}