Active Users by Session Time

You are given a series of session records for different users. Each record is in the format username start_time end_time, where start_time and end_time are in the 24-hour format HH:MM. Your task is to calculate the total session time (in minutes) for each user and print the names of the users whose total session time is at least a given threshold.

Let \(T\) be the total session time for a user. A user is considered active if \[ T \geq \text{threshold} \] Otherwise, the user is not active. The output should be a comma-separated list of active users sorted in alphabetical order. If no user meets the threshold, print an empty string.

inputFormat

The first line contains two integers N and threshold separated by a space, where N is the number of session records.

The next N lines each contain a session record in the format:

username start_time end_time

Here, start_time and end_time are given in 24-hour format (HH:MM).

outputFormat

Print a single line containing a comma-separated list of active users, sorted alphabetically, whose total session time is at least the given threshold. If there are no active users, output an empty string.

3 45
alice 09:00 10:30
bob 11:00 12:00
charlie 15:00 16:00

alice,bob,charlie