def decode(string: str, start: int = 0):
    b = bytes.fromhex(string[start:])
    b0 = b[0]
    return "".join(chr(i ^ b0) for i in b[1:])


if __name__ == "__main__":
    decode("f09c9491b09c949c9491de939f9d", 0)  # lda@ldlda.com