String input has changed from Python2's raw_input(prompt) to Python3's input(prompt). The old Python2 numeric input(prompt) has gone away with Python3, all input is now string input. The snippet shows a few lines you can add to your program such that you only need to use input(prompt). This makes your code usable for both versions of Python.
Python2 coders have always been discouraged to use numeric input(), since it uses raw_input() and eval() internally. The unprotected eval() function can accept OS commands that can delete your disk.