Create a simple python script to parse a given JSON string and print all the keys and their corresponding values.
{"name": "John", "age": 30, "city": "New York"}
import json

json_str = '{"name": "John", "age": 30, "city": "New York"}'
json_data = json.loads(json_str)

for key, value in json_data.items():
    print('{}: {}'.format(key, value))