There's an index column B3:B107 where selected item numbers appear once.

If an item in column A appears also in column B, then insert "1" into column C else insert "0".

I think I can do that with the following formula in column C:

=IF(INDEX(??????,(MATCH(?,??:??,0)),"1","0") - but need help with the INDEX and MATCH, and maybe alot more!

Any help much appreciated.