16.
Lectures A, B, C, D, E and F are to be organised in a span of seven days from Monday to Sunday, only one lecture on each day. One lecture have to be organised only once. One day there will be no lecture. C should be organised immediately before D. E should be before D and there should be gap of two days between E and D. D should be organised before Friday. No lecture should be organised immediately after E. A should be organised on Saturday. F should not be organised on last day.
How many lectures are organised between F and E?