how to build a better calculator in python

1Copynum1 = int(input("num1: "))
2op = input("Operator: ")
3num1 = int(input("num1: "))
4
5if op == "+":
6     print(num1 + num2)
7elif op == "-":
8     print(num1 - num2)
9elif op == "/":
10     print(num1 / num2)
11elif op == "*":
12     print(num1 * num2)
13else:
14     print("Invalid Operator")