looking up for subtotals stretched criteria to count visible cells

[driller]

First of all, i hope this is easy.

Is it possible *?* to have a subtotal() formula in a column that can count
the cells like;

Formula 1) count the visible cells in a column which start with a text "C".

Formula 2) count the visible cells in a column which start with a text "C" &
next number(s) is 2 or more. (e.g. if cell contains text like "C1df",
subtotal will not count, if the cell contains text like "C2dfg" or "C10jky"
or "C6KL", then subtotal will consider to count this.).

Please try to help me on the above subject.