Problem
The program receives information about the phones of all employees of some institution. The first line reports the number of employees N, each of the following N lines has the following format:
<LastName> <Initials> <phone>
where <Lastname> – a string of no more than 20 characters, <Initials> - a string consisting of no more than 4 characters (letter, dot, letter, dot), <phone> – a seven-digit number, 3rd and 4th, i, as well as the 5th and 6th digits of which are separated by the symbol "–". <Surname> and <Initials> as well as <Initials> and <telephone> separated by a single space.
Input string example:
Ivanov P.S. 555-66-77
Employees in the same department have the same phone number. Phone numbers in the institution differ only in the last two digits.
It is required to write the most efficient program that will display information on the screen, how many employees on average work in one unit of this institution.
Output the answer with an accuracy of 6 decimal places.
Запрещенные операторы: sort