Section 152 of companies act 2013

The directors to retire by rotation at every annual general meeting shall be those
who have been longest in office since their last appointment, but as between persons who
became directors on the same day, those who are to retire shall, in default of and subject to
any agreement among themselves, be determined by lot.

1. Agreement among themselves means orally wil do or execution of it is mandatory

2. what does determined by lot means