My solution in Haskell, with lazy evaluation:

fib :: Int -> Int
fib n = last $ take n fibs
  where fibs = 0 : 1 : zipWith (+) fibs (tail fibs)

Solution.scala:14: error: not found: value readInt
         println(fibonacci(readInt()))

first time, it complained about I was not logged in when I was. after refreshing, it showed this

It's sad that for each challenge the majority of comments take the form:

Why is ---------- language not on the list.
OR Please enable ----------- language.

Moderators should make some kind of Disclaimer or something about this.

if(x == 1) 0 else if(x==2 || x==3) 1 else fibonacci(x-1)+fibonacci(x-2)

Scala Code : One liner List.fill(x-1)(0).foldLeft((0,1))( (a,b) => (a._2,a._1+a._2))._1