This problem was added after 1951D - Buying Jewels was deemed too hard to be problem B. At first, we decided to hide the case of swapping with the first stronger cow from the sample test. The testers weren't too impressed:

This problem was originally problem B. It turned out to be too hard and was switched to C, with 1951B - Battle Cows inserted, before being further switched to D as it was still too hard.

It is rather unfortunate that the solution only uses partitions of at most size $$$2$$$, therefore one can solve'' the problem by brute forcing every possible partition and check validity using any string matching algorithm. Nevertheless, we tried our hardest to make sure dumbersolutions'' won't pass.