Write a program that reads two times in military formate(0900, 1730)
and prints the number of hours and minutes between the two times.

Hint:

1. Create a class called Time which has two instance variables, hour and minute, both are integer data types.
    There are two constructors.  One of them is a no-argument constructor that set hour and minute to be zero. 
    The other is taking caller's data to set two instance variables.  In addition to the constructors,
    there are three methods, getHour(), getMinute() and minus().
    getHour(): return hour to caller
    getMinute(): return minute to caller
    public Time minus(Time first):
    pass another object of Time called first.  Calculate that the time of this minus the time of first
    and return the time interval from first object to this object.

2. Write a class included a main function.  Prompt user entering two times in military formate(0900, 1730). 
    Take user information into a String memory box.  Use substring() method to extract hour and minute in string
    then convert to integer (Integer.parseInt() method).  Plot the hours & minutes to a Time constructor
    to get Time objects.  Finally, find the interval from the first time to the second time by calling minus() method..