class Dp:
    def __init__(self, act, param):
        self.act = act
        self.param = param
        self.answers = {
            'request': {
                'imie': "welcomemsg",
                'from': "from",
                'to': "to",
                'time': "date",
                'passangerCount': "travelers_count",
                'discountCount': "travelers_discount_count",
                'seatType': "seat_type",
                'wagonType': "carrige_class",
            }
        }

    def identify(self):
        req = self.answers.get(self.act)
        response = req.get(self.param[0]) if req is not None else "null"
        return response if response is not None else "null"