import java.util.*;

public class Main {

	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
		String[] a = sc.nextLine().split(" ");
		int n = Integer.parseInt(a[0]);
		int x =  Integer.parseInt(a[1]) ;
		int t =  Integer.parseInt(a[2]);
		int answer = 0;
		while (n > 0) {
			n -= x;
			answer += t;
		}
		System.out.println(answer);
	}

}
/tmp/hf-datasets-cache/medium/datasets/42704881117311-config-parquet-and-info-qiankunmu-Project_CodeNet-896c9d36/hub/datasets--qiankunmu--Project_CodeNet_Python800_and_Java250/snapshots/c899fde44a77ba1cc14973ed3de064e4ff3aadc7/Project_CodeNet_Java250.tar.gz