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 returnT = 0;
	    returnT = (int)Math.ceil((double)n / (double)x) * t;
	    System.out.println(returnT);
	}
} 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 returnT = 0;
	    returnT = (int)Math.ceil((double)n / (double)x) * t;
	    System.out.println(returnT);
	}
} 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 returnT = 0;
	    returnT = (int)Math.ceil((double)n / (double)x) * t;
	    System.out.println(returnT);
	} main {
	    Scanner sc = new Scanner(System.in);
	    int n = sc.nextInt();
	    int x = sc.nextInt();
	    int t = sc.nextInt();
	    int returnT = 0;
	    returnT = (int)Math.ceil((double)n / (double)x) * t;
	    System.out.println(returnT);
	} 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 returnT = 0; returnT 0 returnT = (int)Math.ceil((double)n / (double)x) * t returnT (int)Math.ceil((double)n / (double)x) * t (int)Math.ceil((double)n / (double)x) Math.ceil Math (double)n / (double)x (double)n (double)x t System.out.println(returnT) System.out.println System.out System System.out returnT 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 returnT = 0;
	    returnT = (int)Math.ceil((double)n / (double)x) * t;
	    System.out.println(returnT);
	}
} 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 returnT = 0;
	    returnT = (int)Math.ceil((double)n / (double)x) * t;
	    System.out.println(returnT);
	}
} 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 returnT = 0;
	    returnT = (int)Math.ceil((double)n / (double)x) * t;
	    System.out.println(returnT);
	}
}
