case "r":
                        rCount += 1;
                        boolean overFlow3 = overFlow3(stack);
                        if (overFlow3) {
                            System.err.println("Stack overflow.");
                        }
                        else if (rCount > 99) {
                            rCount = 0;
                        }
                        else {
                            stack.push(String.valueOf(a1.get(rCount)));
                        }
                        break;