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