How to NESTING IF STATEMENTS IN EXCEL when the last iteration of character “:” is unknown number of CHARACTERS from the right

Question

Heres my code: =if(left(right($C181,5),1)=":",right($C181,4),if(left(right($C181,6),1)=":",(right($C181,5),if(left(right($C181,7),1)=":",right(