You are using the general purpose System.Collections.Stack which holds objects. Use the generic System.Collections.Generic.Stack<T> [
^]:
Stack<int> yourStack = new Stack<int>(5);
Because Stack is enumerable (Array like), you can read the values using indexes, and iterate without removing them using a 'for or 'foreach loop.
Suggestion: use Int32.TryParse to make sure the user entered an Int: [
^]