Extracting a number from a string under specific conditions

Hi,

I'm struggling on doing something that looks easy (and maybe dumb), but I don't find a way. I need to extract a number from a string that matches specific conditions. I have a column with different strings like:

I want RM to create a new colum that picks only numbers where there is the U in front and leave blank (or put something like none) on the other rows

I'm not able to uniquely identify strings that contains both U and a number after. Is there a way to do that without using python or generativeAI blocks? By using a Split block with a regular expression like [^U[0-9]]{1,} it picks also the U of Amy, while I want select U only if it has followed by a number.

Thanks,

Paolo