
import java.util.Scanner;

/**
 * Created by enpingkuang on 2020/9/10 10:54 下午
 */
public class Main {

    public static void main(String[] args) {
        Scanner scanner = new Scanner(System.in);
        int n = scanner.nextInt();
        int x = scanner.nextInt();
        int t = scanner.nextInt();
        int flag = n % x == 0?0:1;
        System.out.println((n/x + flag)*t);
    }
}

/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