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