
class Student:
    #def sum(self,a,b):
     #   s=a+b
      #  return s
    def sum(self,a=None,b=None,c=None):
        s=0
        if a != None and b != None and c != None:
            s=a+b+c
        elif a != None and b != None:
            s=a+b
        else:
            s=a

        return s




s1= Student()
print(s1.sum(23,2,4))






