No time to Prezify
Hopefully, you'll have time to use the Insert PPT function to the best of your abilities and turn those once-linear slides into something much more interesting. However, not all of us will have the time to reposition content for 50 or so slides, and spend the time required to fully Prezify our PowerPoint slides' content.
If time really is of the essence and you can't afford to waste a single second, you might want to try the following technique to insert your slides as PDF files. This will mean that once imported, everything will stay in exactly the same place that it was in PowerPoint, but on the flip side of that you won't be able to manipulate the individual elements of the slide.
Importing your slides as PDF
If you don't want to go to all the effort of re-arranging the content of your slides in Prezi and simply wish to import the slides as PDF images then follow these steps:
Open the PowerPoint or Keynote file you'd like to import.
In PowerPoint, go to File and click Save...