1class Candy:
 2    def __init__(self, mass, uranium):
 3        self.mass = mass
 4        self.uranium = uranium
 5
 6    def get_uranium_quantity(self):
 7        return self.mass * self.uranium
 8
 9    def get_mass(self):
10        return self.mass
11
12
13class Person:
14    def __init__(self, position):
15        self.position = position
16
17    def get_position(self):
18        return self.position
19
20    def set_position(self, new_position):
21        self.position = new_position
22
23
24class Kid(Person):
25    def __init__(self, position, initiative):
26        super().__init__(position)
27        self.initiative = initiative
28        self.candies = []
29
30    def get_initiative(self):
31        return self.initiative
32
33    def add_candy(self, candy):
34        self.candies.append(candy)
35
36    def is_critical(self):
37        uranium_quantity = sum(candy.get_uranium_quantity() for candy in self.candies)
38        return uranium_quantity > 20
39
40
41class Host(Person):
42    def __init__(self, position, candies):
43        super().__init__(position)
44        self.candies = [Candy(mass, uranium) for mass, uranium in candies]
45
46    def remove_candy(self, choose_candy):
47        if not self.candies:
48            return None
49        chosen_candy = choose_candy(self.candies)
50        self.candies.remove(chosen_candy)
51        return chosen_candy
52
53
54class FluxCapacitor:
55    def __init__(self, participants):
56        self.participants = participants
57
58    def get_victim(self):
59        kids = [participants for participants in self.participants if isinstance(participants, Kid)]
60        hosts = [participants for participants in self.participants if isinstance(participants, Host)]
61        for host in hosts:
62            while kids:
63                serving_kids = [kid for kid in kids if kid.get_position() == host.get_position()]
64                if serving_kids:
65                    serving_kids.sort(key = lambda kid: (-kid.get_initiative(), kid.get_position()))
66                    chosen_kid = serving_kids[0]
67                    candy = host.remove_candy(lambda candies: max(candies, key = lambda candy: candy.get_mass()))
68                    if candy:
69                        chosen_kid.add_candy(candy)
70                        if chosen_kid.is_critical():
71                            return {chosen_kid}
72                    kids.remove(chosen_kid)
73                else:
74                    break
75        return None