import java.util.Scanner;
public class Main {
  public static void main(final String[] args){
    Scanner scan = new Scanner(System.in);
    int n = scan.nextInt();
    int x = scan.nextInt();
    int t = scan.nextInt();
    int count = 0;
   
    while(n>0){
      n = n - x;
      count++;
    }
    System.out.println(t*count);
  }
}
/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