class Phone:
    def __init__(self,brand,model_name,price):
        self.brand=brand
        self.model_name=model_name
        self._price=max(price,0)
        
    def full_name(self):
        return f"{self.brand} {self.model_name}"
    def make_a_call(self,number):
        return f'calling {number}......'
    
class Smartphone(Phone):
     def __init__(self,brand,model_name,price,ram,internal_memory,rear_camera):
        #  Phone.__init__(self,brand,model_name,price)
         super().__init__(brand,model_name,price)
         self.ram=ram
         self.internal_memory=internal_memory
         self.rear_camera=rear_camera
         
phone =Phone("nokia",'1100',1000)
smartphone=Smartphone('oneplus','5',30000,'6 gb','64 gb','20 mp')
print(phone.full_name())
print(smartphone.full_name())