import java.util.Scanner;

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

		// 入力値の取得
		int N = sc.nextInt();
		int X = sc.nextInt();
		int T = sc.nextInt();
		
		// 結果の出力
		if (N % X == 0) {
			System.out.println((N / X ) * T);
		}
		else {
			System.out.println(((N / X) + 1) * 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);

		// 入力値の取得
		int N = sc.nextInt();
		int X = sc.nextInt();
		int T = sc.nextInt();
		
		// 結果の出力
		if (N % X == 0) {
			System.out.println((N / X ) * T);
		}
		else {
			System.out.println(((N / X) + 1) * T);
		}
		
		sc.close();
	}
} Main public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);

		// 入力値の取得
		int N = sc.nextInt();
		int X = sc.nextInt();
		int T = sc.nextInt();
		
		// 結果の出力
		if (N % X == 0) {
			System.out.println((N / X ) * T);
		}
		else {
			System.out.println(((N / X) + 1) * T);
		}
		
		sc.close();
	} main {
		Scanner sc = new Scanner(System.in);

		// 入力値の取得
		int N = sc.nextInt();
		int X = sc.nextInt();
		int T = sc.nextInt();
		
		// 結果の出力
		if (N % X == 0) {
			System.out.println((N / X ) * T);
		}
		else {
			System.out.println(((N / X) + 1) * 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 if (N % X == 0) {
			System.out.println((N / X ) * T);
		}
		else {
			System.out.println(((N / X) + 1) * T);
		} N % X == 0 N % X N X 0 {
			System.out.println((N / X ) * T);
		} System.out.println((N / X ) * T) System.out.println System.out System System.out (N / X ) * T (N / X ) N X T {
			System.out.println(((N / X) + 1) * T);
		} System.out.println(((N / X) + 1) * T) System.out.println System.out System System.out ((N / X) + 1) * T ((N / X) + 1) (N / X) N X 1 T sc.close() sc.close sc String[] args args public class Main {
	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);

		// 入力値の取得
		int N = sc.nextInt();
		int X = sc.nextInt();
		int T = sc.nextInt();
		
		// 結果の出力
		if (N % X == 0) {
			System.out.println((N / X ) * T);
		}
		else {
			System.out.println(((N / X) + 1) * T);
		}
		
		sc.close();
	}
} public class Main {
	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);

		// 入力値の取得
		int N = sc.nextInt();
		int X = sc.nextInt();
		int T = sc.nextInt();
		
		// 結果の出力
		if (N % X == 0) {
			System.out.println((N / X ) * T);
		}
		else {
			System.out.println(((N / X) + 1) * T);
		}
		
		sc.close();
	}
} Main
import java.util.Scanner;

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

		// 入力値の取得
		int N = sc.nextInt();
		int X = sc.nextInt();
		int T = sc.nextInt();
		
		// 結果の出力
		if (N % X == 0) {
			System.out.println((N / X ) * T);
		}
		else {
			System.out.println(((N / X) + 1) * T);
		}
		
		sc.close();
	}
}
