class A:

    def __init__(self, a):
        self.chislo = a

    def __eq__(self, other):
        return self.chislo == other.chislo

    def __str__(self):
        return f'chisloto e {self.chislo}'

class B:

    def __init__(self):
        self.obekti = []

    def find(self, obj):
        found = False
        for x in self.obekti:
            if x.chislo == obj:
                found = True
        return found

    def kotka (self, obj):
        self.obekti.append(obj)

    def __add__(self, obj):
        self.obekti.append(obj)
        return self

    def __str__(self):
        temp = ""
        for x in self.obekti:
            temp += str(x) + "\n"
        return temp


a = A(12)
b = A(23)
c = B()
c.kotka(a)
c = c + b

print(a)

print(c)