Upvote:1
Maybe an easier way to think about duration of stay: If you enter 26 Dec, and leave 27 Dec, you have spent 2 days.
Even if hypothetically it was 23:59 on 26 Dec and you left 2 minutes after at 00:01 on 27 Dec.
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Upvote:2
For the Schengen visa they count every day you have been within the zone as a day, even when you have been in just a few minutes.
So with your plans you would overstay by one day. And while you are not guarantied to get problems later it is rather likely that you get a mark in your passport or may have to face extra questions when getting into the Schengen zone again.
Better to change your return flight or spend some time outside the Schengen zone. With a multiple entry visa is it possible to do just that.