Convert PPTX to KEYNOTE

Keynote accepts formats from Microsoft PowerPoint (.ppt, .pptx, .pps, .ppsx) and can open and further work with them. It also allows saving them to the default .key (or previously .keynote) format. Unfortunately, the older .keynote files cannot be produced in latest version of Keynote, so you have to use some of the earlier version of the app to achieve pptx to keynote conversion as the latest will only allow pptx to key conversion.