import strutils

proc nextString: string =
    result = ""
    while not endOfFile stdin:
        let c = readChar stdin
        if c == ' ' or c == "\n"[0]: return
        elif c != '\r': add result, c

proc nextInt: int =
    parseInt nextString()


let
    f0, f1, n = nextInt()
    f = [f0, f1, f0 xor f1]

echo f[n mod 3]