What pattern or (loops and patterns) can find all possible character in word and keep sequence of founded in LUA

I want to take each founded character in any word

str = "ABC" str:match("(A?)(B?)(C?)") if u can see I don't know any character of str. but i wanna see them if they found.

but what if

str = yyyyAyyyyByyyyCyyyy print( str:match(?) ) -- like "(A?).-(B?).-(C?)" --> A, B, C str = yyCyyAyyyyByyyyyyyy print( str:match(?) )" --> A, B str = yyCyyyyyyyByyyyyCyyy print( str:match(?) )" --> B, C

the word can be in any variation, just any. Hoh to do that pattern or loop if patterns is useless. I am dumb give me just a working code =)