let ``No.64 XORフィボナッチ数列``() =
    let f (s:string) =
        let arr = s.Split(' ') |> Array.map bigint.Parse
        let n = arr.[2]
        arr.[2] <- arr.[0] ^^^ arr.[1]
        arr.[int(n % 3I)]
    f <| stdin.ReadLine() |> printfn "%A"
``No.64 XORフィボナッチ数列``()