It is very important to name arguments in a certain order, so that the flow directions will not be confusing when they move in multiple xamls. In your case, you can name it as io_counter.
Since you are sending the argument from main to seq1 & want that back till main, you can mention the direction as in/out. Once you make changes to the counter in seq1 & sending it to seq2, it is important to keep the direction again as in/out. By this way, any changes made in seq2 will come back to seq1 & the same argument flow till main.
If you wish to create a global variable for the same, you can refer this thread: