private int getNumberOfSimulations() {
        while (true) {
            System.out.println("");
            System.out.println("Number of simulations (select default 10000 by pressing enter): ");
            String input = scanner.nextLine().trim();
            
            if (input.isEmpty()) {
                return 10000;
            }            
            try {
                return Integer.parseInt(input);                
            } catch (NumberFormatException e) {
                System.out.println("Invalid input");
            }                
        }
    }