import java.util.*;
import static java.lang.System.*;

class Main{
  public static void main(String[] a){
    Scanner sc = new Scanner(in);
    int n = sc.nextInt();
    int x = sc.nextInt();
    int t = sc.nextInt();
    
    int y = (n+x-1)/x;
    out.print(y * t);
  }
} import java.util.*; util.* java import static java.lang.System.*; import static java.lang.System.*; import static java.lang.System.*; class Main{
  public static void main(String[] a){
    Scanner sc = new Scanner(in);
    int n = sc.nextInt();
    int x = sc.nextInt();
    int t = sc.nextInt();
    
    int y = (n+x-1)/x;
    out.print(y * t);
  }
} Main public static void main(String[] a){
    Scanner sc = new Scanner(in);
    int n = sc.nextInt();
    int x = sc.nextInt();
    int t = sc.nextInt();
    
    int y = (n+x-1)/x;
    out.print(y * t);
  } main {
    Scanner sc = new Scanner(in);
    int n = sc.nextInt();
    int x = sc.nextInt();
    int t = sc.nextInt();
    
    int y = (n+x-1)/x;
    out.print(y * t);
  } Scanner sc = new Scanner(in); sc new Scanner(in) int n = sc.nextInt(); n sc.nextInt() sc.nextInt sc int x = sc.nextInt(); x sc.nextInt() sc.nextInt sc int t = sc.nextInt(); t sc.nextInt() sc.nextInt sc int y = (n+x-1)/x; y (n+x-1)/x (n+x-1) n+x n x 1 x out.print(y * t) out.print out y * t y t String[] a a
import java.util.*;
import static java.lang.System.*;

class Main{
  public static void main(String[] a){
    Scanner sc = new Scanner(in);
    int n = sc.nextInt();
    int x = sc.nextInt();
    int t = sc.nextInt();
    
    int y = (n+x-1)/x;
    out.print(y * t);
  }
}