Entering a number and calculating it.

[Yura_Yusko]

Hi to all.
I have a fairly simple question.
I need to create an input type action.
Get a number (negative or positive) from the user and add this number to the value stored in the table cell.
That's all.

I tried something like that:
([Amount] + NUMBER(INPUT(value, 0)))
... but it doesn't work.