635. Design Log Storage System

["LogSystem","put","put","put","retrieve","retrieve"]
[[],[1,"2017:01:01:23:59:59"],[2,"2017:01:01:22:59:59"],[3,"2016:01:01:00:00:00"],["2016:01:01:01:01:01","2017:01:01:23:00:00","Year"],["2016:01:01:01:01:01","2017:01:01:23:00:00","Hour"]]