C++ Taskbook Level 6.4

Ask the user to enter an integer via the console. Get the factorial of the entered number.

Ask the user to enter a date in the format year-month-day. Check if they entered the value in the correct format.

Determine how many days are left until the New Year.

Given a string containing time in the format hours:minutes:seconds:

Check that the time is correct: hours from 00 to 23, minutes and seconds from 00 to 59.

Given a string:

Remove from this string all substrings in which the number of characters is more than three. In our case, we should get the following: