Hopefully, this is a nonsensical homework question and not something you've actually coded, because there's no reason - other than academic exercise - to obscure code's real purpose with such useless complexity.
Here, I will write you a little example to try to explain it. When you write ++, it is called increment -- is decrement. If you do ++ before a variable name it increments the variable by 1 before it running it. If you were to do a variable then ++ then it would increment it after here is an example:
int x = 10;
// This would print out 11 because even though x is 10, it is incremented before printing it.
/* If I were to write this it would print out 10, but then next I printed x it would be 11 because * it is incremented after printing it.
* All the same applies to -- as that is just doing minus 1 instead of plus 1