Adding up columns of a cell

I have a 10x60 cell (let’s call it A). I want to make a new cell (B) from this old one where I add certain values of the columns together so that I get a new 10x40 cell (this new cell will be smaller because 20 columns will be added up together). I have another cell 10x20 (C), that has the index of all the columns in A that need to be added together. How can I do this efficiently?

(note, the class of the things in the cells are "char")

[dpb]

What does it mean to add " things in the cells are "char"?

Think we need to see a (small) sample problem of inputs and expected outputs.

[Jan]

Does "adding" mean a concatenation, if the contents of the cell elements are char vectors?

[Sai Veeramachaneni]

When 20 columns are added together, new cell array will be of 10x41 instead of 10x40. Can you provide with an example of what you are trying to do?