import java.util.Scanner;

public class Prog6
{
    public static void main(String[] args)
    {
        Scanner stdIn = new Scanner(System.in);
        String selection;
        char sel;
        double money,balance = 0,wthdrwl,interest = .04;
        do
        {
            System.out.print("D - Deposit\nW - Withdraw\nI - Interest\nB - Balance\nQ - Quit\nSelection: ");
            selection = stdIn.nextLine();
            selection = selection.toUpperCase();
            sel = selection.charAt(0);
            if (sel == 'D')
            {
                do
                {
                    System.out.print("Amount of deposit: ");
                    money = stdIn.nextDouble();
                    if (money < 0)
                    {
                        System.out.println("You can't deposit a negative amount of money.");
                    }
                    else
                    {
                        balance = money + balance;
                        System.out.println("Your new balance is: " + balance);
                    }
                } while (money < 0);
            }
            if (sel == 'W')
            {
                if (balance <= 0)
                {
                    System.out.println("Unable to withdraw. Balance = $0. Returning to menu.");
                }
                if (balance > 0)
                {
                    do
                    {
                        System.out.print("Withdraw Amount: ");
                        wthdrwl = stdIn.nextDouble();
                        if (wthdrwl > balance || wthdrwl <= 0)
                        {
                            System.out.println("ERROR: Withdrawl is less than or equal to $0 or exceeds account balance.");
                        }
                        else
                        {
                            balance = balance - wthdrwl;
                            System.out.println("Your new balance is: " + balance);
                        }
                    } while (wthdrwl > balance || wthdrwl <= 0);
                }
            }
            if (sel == 'I')
            {
                if (balance <= 0)
                {
                    System.out.println("Cannot compute interest on negative or $0 balance.");
                }
                else
                {
                    balance = (balance * interest) + balance;
                    System.out.println("Interest computed.\nNew balance: " + balance);
                }
            }
            if (sel == 'B')
            {
                System.out.println("Current balance: " + balance);
            }
        } while (sel != 'Q');
    }
}