Hello, sorry I didn't got it quite well, I'll try to explain it better this
time my sheet has something like this example:

0 A B C a b c
1 B C D b c d
2 C D E c d e
3 D E F d e f

So what I need is some sort of lookup which is case sensitive where I have
already for example letter "C" and in a cell I type "2" so that means I
should get "E", if I type "3" then i should get "F" and so on... I didn't get
how I should put that into the formula, thanks!