Semaphore implementation

Hello,
I want to know how to implement semaphore without the use of while or any if statement
The Problem is
Thread A , B , C they all want to output the result at the same time
A wants ot print 'A'
B wants to print 'B'
C wants to print 'C'
the output must be 'ABC'. I do not know how to do this.Please help me with the same
Regards
Sonu

 

but how would i implement a semaphore for that