Write a Python progr . Suppose that there are N events to be held this year. The ith event is scheduled from day si to day ti, and free food is to be served for that event every day from day si to ti (inclusive). Your task is to find out how many days there are in which free food is served by at least one event. Write a function called calculate that takes a list of strings containing the start and end days to solve this problem. Your main function will only read in the inputs and pass those inputs as a list to the calculate function (see the provided template for more information). Example Let N = 3 events. first event is held from day 10 to 14, the second event is held from day 13 to 17, and the third event is held from day 25 to 26. The days in which free food is served by at least one event are 10, 11, 12, 13, 14, 15, 16, 17, 25, 26, for a total of 10 days. Note that both events serve free food on days 13 and 14, and therefore they are only counted once. Input The first line the user will supply you is an integer, N, denoting the number of events. Each of the next N lines contains two integers si and ti denoting that the ith event will be held from si to ti (inclusive), and free food is served for all of those days.