Uuuh?? Ok, let us go back to the basics, shall we? First, we must know that , so we get that .
Second...what I already wrote in my past messages: as is a finite group of order m, any of its elements raised to the m-th power is the group's unit, and this means that . But , according to the definition of the operation that makes a group, so this togehter with the first lines in this message gives...
Tonio