It is interesting for me to remember my very first programming task. The very first day I was introduced to programming with Pascal (I think I was 14), I was taught variables, assignments, arithmetic and was given a task to switch two variables (swap). I quickly solved it using third variable, but then I was asked to do it without third variable. It was very hard task for me, I spent few hours at home tackling it, but finally I solved it with a trick conceptually similar to XOR:
a := a + b;
b := a - b;
a := a - b;
I'm still proud of little me and I always remember this solution when I encounter XOR tricks. I didn't knew about bitwise arithmetic at that time, but sometimes simple `+` can work just as well.
It doesn't matter. Overflow is a non-issue as long as you have wrapping addition and subtraction operators, which C# does - regular `+` and `-` not inside `checked {}`. You don't need to reach for BigInteger.
