Write a full class definition for a class named Counter, and containing the following members:

1. A data member counter of type int.
2. A constructor that takes one int argument and assigns its value to counter
3. A function called increment that accepts no parameters and returns no value. increment adds one to the counter data member.
4. A function called decrement that accepts no parameters and returns no value. decrement subtracts one to the counter data member.
5. A function called getValue that accepts no parameters. It returns the value of the instance variable counter.