Define a default constructor that initializes the fields number $($integer$),$ greeting $($string$),$ and areaCode $($integer$)$ with the default values $0,$ "Unknown", and $1,$ respectively.

Ex: If the input is $9226765$ Bob $953,$ then the output is:

Default values:

Number: $0,$ Greeting: Please leave a message for Unknown, Area code: $1$

After mutator methods:

Number: $9226765,$ Greeting: Please leave a message for Bob, Area code: $953$