Six lectures A, B, C, D, E and F are to be organised in a spam of seven days -- from Sunday to Saturday, only one lecture on each day in accordance with the following :
A should not be organised on Thursday.
C should be organised immediately after F.
There should be a gap of two days between E and D.
One day there will be no lecture (Friday is not that day), just before that day D will be organised.
B should be organised on Tuesday and should not be followed by D.