public class Main {
    public static int getFactorialForLoop(int n) {
        int result = 1;
        if (n > 1) {
            for (int i = 1; i <= n; i++) {
                result = result * i;
            }
            return result;
        } else {
            System.out.println("n has to be positive");
            return result;
        }
    }

    public static class Fibonacci {
        public int fibonacciIterative(int n) {
            if (n <= 1) {
                return n;
            }
            int fib = 1;
            int prevFib = 1;

            for (int i = 2; i < n; i++) {
                int temp = fib;
                fib += prevFib;
                prevFib = temp;
            }
            return fib;
        }

        public static void main(String[] args) {
            Fibonacci fib = new Fibonacci();

            System.out.println("Iterative version:");
            System.out.println(fib.fibonacciIterative(5));
            System.out.println(fib.fibonacciIterative(10));
            System.out.println(fib.fibonacciIterative(20));
            System.out.println(fib.fibonacciIterative(30));
        }
    }
}