Amazon has the FDTEK Universal Travel Adapter with 4 USB ports (https://www.amazon.com/dp/B0CGRCMMLF?tag=quackdeals-20) for just $11.99 (with Prime membership) - use code SD45FDTEK at checkout. This handy adapter works in over 300 countries with plugs for Europe, UK, Australia, China, and more.
(https://m.media-amazon.com/images/I/71dtSC0LxiL._AC_SL1500_.jpg)