Excel function

Hello,

I'm looking for a function in Excel.

I have 3 sheets:

- 1st sheet: a list of items and the names of them

- 2nd sheet: same as 1st sheet

- 3rd sheet: a summary of all the unique items from the sheets above.

I need a function to bring me the name of the products from the first sheet, and if it doesn't find it in the first sheet, bring it from the second sheet.

Thank you!