import java.util.Scanner;

class Fibonacci {
	public static void main(String[] args) {
		Scanner skn = new Scanner(System.in);
		int n;
		long res;
		try {
            n = skn.nextInt();
        } catch (java.util.InputMismatchException e) {
            System.out.println("Invalid input!");
            skn.close();
            return;
        }
		
		if (n < 1) {
			System.out.println("Invalid input! n cannot be negative!");
            skn.close();
            return;
		}

		double sqrt5 = Math.sqrt(5);
		res = Math.round((1/sqrt5) * (Math.pow((1 + sqrt5) / 2, n) - (Math.pow((1 - sqrt5) / 2, n))));
		if (res > Integer.MAX_VALUE) {
			System.out.println("Overflow!");
		} else {
			System.out.println(n + ". Fibonacci number: " + res);
		}

		skn.close();
	}
}