Debug: Every Button Fires Three Times

Classic bug: a loop registers three "print i" lambdas, but pressing any single button prints 3 — the last value. Build below reproduces it. Fix Build so each lambda remembers its OWN index, and keep Sum as is (it is correct). ``csharp static List<Func<int>> Build(int n); // lambda i returns i static int Sum(List<Func<int>> fs); // invoke all, total ``