Six lectures A1, A2, A3, A4, A5 and A6 are to be organized in a span of seven days from Sunday to Saturday. Only one lecture on each day in accordance with the following:
I. There should be a gap of two days between A5 and A4.
II. A2 should be organised on Tuesday and should not be organized just before A4.
III. Al should not be organized on Thursday.
IV. One day there will be no lecture (Friday is not that day), just before that day A4 will be organised.
V. A3 should be organised immediately after A6. On which day there is no lecture?