import java.util.Scanner;

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

		int ans = (int) ((Math.ceil(n / x)) * t);
		System.out.println(ans);
		sc.close();
	}
}

 import java.util.Scanner; Scanner java.util public class Main {
 
	public static void main(String[] args) {
		
		Scanner sc = new Scanner(System.in);
		double n  = sc.nextDouble();
		double x  = sc.nextDouble();
		double t  = sc.nextDouble();

		int ans = (int) ((Math.ceil(n / x)) * t);
		System.out.println(ans);
		sc.close();
	}
} Main public static void main(String[] args) {
		
		Scanner sc = new Scanner(System.in);
		double n  = sc.nextDouble();
		double x  = sc.nextDouble();
		double t  = sc.nextDouble();

		int ans = (int) ((Math.ceil(n / x)) * t);
		System.out.println(ans);
		sc.close();
	} main {
		
		Scanner sc = new Scanner(System.in);
		double n  = sc.nextDouble();
		double x  = sc.nextDouble();
		double t  = sc.nextDouble();

		int ans = (int) ((Math.ceil(n / x)) * t);
		System.out.println(ans);
		sc.close();
	} Scanner sc = new Scanner(System.in); sc new Scanner(System.in) double n  = sc.nextDouble(); n sc.nextDouble() sc.nextDouble sc double x  = sc.nextDouble(); x sc.nextDouble() sc.nextDouble sc double t  = sc.nextDouble(); t sc.nextDouble() sc.nextDouble sc int ans = (int) ((Math.ceil(n / x)) * t); ans (int) ((Math.ceil(n / x)) * t) (Math.ceil(n / x)) Math.ceil Math n / x n x t System.out.println(ans) System.out.println System.out System System.out ans sc.close() sc.close sc String[] args args public class Main {
 
	public static void main(String[] args) {
		
		Scanner sc = new Scanner(System.in);
		double n  = sc.nextDouble();
		double x  = sc.nextDouble();
		double t  = sc.nextDouble();

		int ans = (int) ((Math.ceil(n / x)) * t);
		System.out.println(ans);
		sc.close();
	}
} public class Main {
 
	public static void main(String[] args) {
		
		Scanner sc = new Scanner(System.in);
		double n  = sc.nextDouble();
		double x  = sc.nextDouble();
		double t  = sc.nextDouble();

		int ans = (int) ((Math.ceil(n / x)) * t);
		System.out.println(ans);
		sc.close();
	}
} Main
import java.util.Scanner;

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

		int ans = (int) ((Math.ceil(n / x)) * t);
		System.out.println(ans);
		sc.close();
	}
}


