class Adder:
    def go(self, a, b):
        return a + b


class Subtractor:
    def go(self, a, b):
        return a - b


adder = Adder()
# adder.go(2, 6) --> 8
subber = Subtractor()
# subber.go(2, 6) --> -4
operations = {
    "+": adder,
    "-": subber
}
inp = ' '
while inp != '':
    inp = input("a op b>>")
    a, op, b = inp.split(" ")
    a = int(a)
    b = int(b)
    operator = operations[op]
    print("Result:", operator.go(a, b))