import java.util.*;

class Fibo2 {

    static final Scanner input = new Scanner(System.in);

    static long fibo0(int n, long fn1, long fn)
    {
        if (n == 0)
            return fn;
        else
            return fibo0(n - 1, fn, fn1 + fn);
    }

    static long fibo(int n)
    {
        return fibo0(n, 1, 0);
    }

    public static void main(String[] args) {
        int n;
        System.out.print("n? ");
        n = input.nextInt();
        System.out.println("F(" + n + ") = " + fibo(n));
    }
}