int fib(int n) =
  if n < 2 then n
           else fib(n-1) + fib(n-2)

int ifib(int n) =
  if n < 2 then n else do
    int current = 1;
    int previous = 1;
    while n > 2 do
      int sum = current + previous;
      previous = current;
      current = sum;
      n = n-1;
    done;
    current;
  done


void main() = do
  print ifib(100000*12.3*'a');
done