Match dates in two colums, then insert value next to matched date

I have two columns of dates, these are in a random order in C2. In E2 the dates are in sequence.

The dates in C2 may or may not exist in E2, and there maybe blank cells interspersed in Column C.

I've been trying to achieve this with index/match but just can't get it to work.

If the date is found in Col C & E, place a value from A1 next to the date in Col E.

Any help appreciated.

Thanks

Edit : The dates in column C may occur more than once, but only once in Col E