import java.util.Scanner;

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 amari = N % X;
		    if(amari != 0) {
		    	int sho = N / X + 1;
		    	System.out.println(sho * T);
		    }else {
		    	int sho = N / X;
		    	System.out.println(sho * 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