Question

The current selected programming language is Python. We emphasize the submission of a fully working code over partially correct but efficient code. Use of certain header files is restricted. Once submitted, you cannot review this problem again. You can use print to debug your code. The print may not work in case of syntax$/$runtime error. The version of Python being used is $2\mathrm{.}7.$

A dance institute provides morning and evening sessions. Every person who joins the institute is provided a unique ID$.$ Persons can choose any number of dance forms. Some people who are not very perfect in any dance form attends both the sessions. The dance trainer prepares a separate list for the morning and evening session of all the persons who attend the session. The ID of the persons is repeated in the list by the same number of times as the number of dance forms he$/$she has chosen.

The institute has planned to showcase various dance forms on the annual event. The institute wants some leaders who can lead the event on the final day. So$,$ the