import java.util.*;

public 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();
    
    int num = N / X;
    if(N % X != 0) ++ num;
    
    System.out.println(num * T);
  }
} import java.util.*; util.* java public 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();
    
    int num = N / X;
    if(N % X != 0) ++ num;
    
    System.out.println(num * T);
  }
} 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();
    
    int num = N / X;
    if(N % X != 0) ++ num;
    
    System.out.println(num * T);
  } main {
    Scanner sc = new Scanner(System.in);
    int N = sc.nextInt();
    int X = sc.nextInt();
    int T = sc.nextInt();
    
    int num = N / X;
    if(N % X != 0) ++ num;
    
    System.out.println(num * T);
  } Scanner sc = new Scanner(System.in); sc new Scanner(System.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 num = N / X; num N / X N X if(N % X != 0) ++ num; N % X != 0 N % X N X 0 ++ num num System.out.println(num * T) System.out.println System.out System System.out num * T num T String[] args args public 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();
    
    int num = N / X;
    if(N % X != 0) ++ num;
    
    System.out.println(num * T);
  }
} public 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();
    
    int num = N / X;
    if(N % X != 0) ++ num;
    
    System.out.println(num * T);
  }
} Main
import java.util.*;

public 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();
    
    int num = N / X;
    if(N % X != 0) ++ num;
    
    System.out.println(num * T);
  }
}