import java.util.Scanner;


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

		int n = scan.nextInt();
		int x = scan.nextInt();
		int t = scan.nextInt();
		int temp = 0;
		if(n % x != 0 ) {
			temp = 1;
		}

		System.out.print(((n / x) + temp) * t);
	}
} import java.util.Scanner; Scanner java.util public class Main {
	public static void main (String args[]) throws Exception{
		Scanner scan = new Scanner(System.in);

		int n = scan.nextInt();
		int x = scan.nextInt();
		int t = scan.nextInt();
		int temp = 0;
		if(n % x != 0 ) {
			temp = 1;
		}

		System.out.print(((n / x) + temp) * t);
	}
} Main public static void main (String args[]) throws Exception{
		Scanner scan = new Scanner(System.in);

		int n = scan.nextInt();
		int x = scan.nextInt();
		int t = scan.nextInt();
		int temp = 0;
		if(n % x != 0 ) {
			temp = 1;
		}

		System.out.print(((n / x) + temp) * t);
	} main {
		Scanner scan = new Scanner(System.in);

		int n = scan.nextInt();
		int x = scan.nextInt();
		int t = scan.nextInt();
		int temp = 0;
		if(n % x != 0 ) {
			temp = 1;
		}

		System.out.print(((n / x) + temp) * t);
	} Scanner scan = new Scanner(System.in); scan new Scanner(System.in) int n = scan.nextInt(); n scan.nextInt() scan.nextInt scan int x = scan.nextInt(); x scan.nextInt() scan.nextInt scan int t = scan.nextInt(); t scan.nextInt() scan.nextInt scan int temp = 0; temp 0 if(n % x != 0 ) {
			temp = 1;
		} n % x != 0 n % x n x 0 {
			temp = 1;
		} temp = 1 temp 1 System.out.print(((n / x) + temp) * t) System.out.print System.out System System.out ((n / x) + temp) * t ((n / x) + temp) (n / x) n x temp t String args[] args public class Main {
	public static void main (String args[]) throws Exception{
		Scanner scan = new Scanner(System.in);

		int n = scan.nextInt();
		int x = scan.nextInt();
		int t = scan.nextInt();
		int temp = 0;
		if(n % x != 0 ) {
			temp = 1;
		}

		System.out.print(((n / x) + temp) * t);
	}
} public class Main {
	public static void main (String args[]) throws Exception{
		Scanner scan = new Scanner(System.in);

		int n = scan.nextInt();
		int x = scan.nextInt();
		int t = scan.nextInt();
		int temp = 0;
		if(n % x != 0 ) {
			temp = 1;
		}

		System.out.print(((n / x) + temp) * t);
	}
} Main
import java.util.Scanner;


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

		int n = scan.nextInt();
		int x = scan.nextInt();
		int t = scan.nextInt();
		int temp = 0;
		if(n % x != 0 ) {
			temp = 1;
		}

		System.out.print(((n / x) + temp) * t);
	}
}