List all airlines. For every airline, compute the number of regional airports (full name of airport contains the string 'Regional') from which that airline does NOT fly, considering source airport only. Sort by airport count in descending order. In case of ties, sort by airline name A-Z.
The dataset consists of the following files:
- airlines.csv : list of airlines
- airports.csv : list of airports
- flights.csv : list of flights
Individual files have the following formats.

airlines.csv
Id : unique identifier of the airline
Name : full name of the airline
Abbr : abbreviated name of the airline
Country : country of the airline

airports.csv
City : location of the airport
Code : unique three-letter airport code
Name : name of the airport
Country : country of the airport
CAbbr : abbreviation of the country
**
flights.csv
Airline : airline that manages the flight
FlightNo : flight number (unique for each airline, may repeat
for different airlines)
Source : Code for the airport from which the flight originates
Destination : Code for the airport at which the flight terminates

An airport that serves a geographical area that is relatively small or sparsely inhabited is known as a regional airport. Customs and immigration facilities to handle international traffic are typically not available at rural airports.

Which of these three airport types are they?

Airports that provide non-primary commercial service, relief flights, and general aviation are all included in this category. Based on their activity, nonprimary airports are assigned a position in the federal airport system.

What makes airports significant?

Major cities and small towns are connected 24 hours a day with increasingly sophisticated aircraft through a network of airlines, airports, and air traffic control organizations. With 87.7 million employment supported globally and 11.3 million direct jobs, the airline industry is a significant employer on a global scale.

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