Func Fibonacci(n) = if n<0 then -(-1)^n*Fibonacci(-n) else if n<2 then n else
    Array fib[n+1];
    fib[1] := 0;
    fib[2] := 1;
    for i = 2, n do
    fib[i+1]:=fib[i]+fib[i-1]
    od;
    Return(fib[n+1]);
    fi;
    fi;
    .