Your first instinct of chef is right. It counts the pairs on the whole line. But not itself.
For instance, a number learns that there're 2 pairs of even. Then there might be 2,4,6. Or 2,4 ... 6,8.
I reached an issue, I can't scroll down on case 5 to see stuff.
Thx for feedbacks! Fixing right now.
I noticed you updated the game, but it still isn't fixed.