using System;
using System.Console;

module Fib
{
    Fib(n : long) : long
    {
        def fib(m : long)
        {
            |0 => 1
            |1 => 1
            |_ => fib(m - 1) + fib(m - 2)
        }

        match(n)
        {
            |n when (n < 0) => throw ArgumentException("Fib() not defined on negative numbers")
            |_ => fib(n)
        }
    }

    Main() : void
    {
        foreach (i in [-2 .. 10])
        {
            try {WriteLine("{0}", Fib(i));}
            catch {|e is ArgumentException => WriteLine(e.Message)}
        }
    }
}