// base class of account:

public class account
{
    // a "private" variable is not visible outside of the class account
    // a "protected" variable is also visible in subclasses of account
    // a "public" variable is visible from all other classes and packages

    // If a variable is not preceeded by public/protected/private, then it's
    // by default public inside the same package (basically, same directory).

   protected double balance;
   public account(double n) { balance=n; }

    public void deposit(double amt) { balance += amt; }
    public void withdraw(double amt) { if (amt<=balance) balance -=amt; }
    public double inquiry() { return balance; }
}


// subclass "savings" account has an interest rate, which is added to deposits

class savings extends account
{
   protected static double interestrate = 0.01;  // 1% interest (why static?)

   public savings(double n) { super(n); }  // just call superclass constructor

   public void deposit(double amt) // override deposit method of superclass
    {  balance +=  amt + (amt * interestrate); }
}


// subclass "checking" account charges a fee for each withdraw

class checking extends account
{
    protected double fee;  // fee charged for each withdraw
    
    public checking(double n) 
      { super(n); 
        if (n<1000) fee = 2; else fee = 1;  // fee depends on initial balance
      }
    
    // override withdraw method of superclass
    
    public void withdraw(double amt)
    { if (amt+fee<=balance) balance -= amt+fee; }
}