long Fn_non_recursive2(int n) {
		if (n <= 0)
			return 0;
		if (n == 1)
			return 1L;

		long fn2 = 0;
		long fn1 = 1;
		long fn = fn1 + fn2;

		for (int i = 2; i <= n; i++) {
			fn = fn1 + fn2;
			fn2 = fn1;
			fn1 = fn;
		}

		return fn;
	}