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