Simple game score calculation

Hello, sorry my english is lousy.

I'm wondering if there is formula that i can calculate finnish "mölkky" game scores?

These are rules; you get points after falling sticks (if any falls). Points are 0-?. Goal is to get 50 points. If you get over 50 points, then points go back 25 points.

As you see (attachment) Matts points are 51, so he has now 25 points. Help please!

Thank You!

Sieppaa.JPG

formula in I6

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I think this is pretty close, but Excel says "Failure in formula".