
/*
 *   
 *   Date: 07 September 2019
 *   Time: 01:03:00
*/
import java.io.*; 
import java.util.*;


   
 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();
        long a=(long)Math.ceil((double)n/x);
        long b=a*t;
        System.out.println(b);
     
        
       

       
    } 
} 
 
 
 

/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