(1) Create a new class called SavingsAccount that extends BankAccount.(2) It should contain an instance variable called rate that represents the annual interest rate. Set it equal to 2.5%.(3) It should also have an instance variable called savingsNumber, initialized to 0. In this bank, you have one account number, but can have several savings accounts with that same number. Each individual savings account is identified by the number following a dash. For example, 100001-0 is the first savings account you open, 100001-1 would be another savings account that is still part of your same account. This is so that you can keep some funds separate from the others, like a Christmas club account.(4) An instance variable called accountNumber that will hide the accountNumber from the superclass, should also be in this class.(5) Write a constructor that takes a name and an initial balance as parameters and calls the constructor for the superclass. It should initialize accountNumber to be the current value in the superclass accountNumber (the hidden instance variable) concatenated with a hyphen and then the savingsNumber.(6) Write a method called postInterest that has no parameters and returns no value. This method will calculate one month