Hello everyone!

Here is the link to the problem: https://codeforces.com/contest/1504/problem/B

In the 5th test case, $$$A$$$ can be converted to $$$B$$$ as:

000111 -> [000111] -> 111000
111000 -> 11[10]00 -> 110100

As, both the prefix contains equal $$$1$$$ and $$$0$$$, so I think this is correct. But, the answer says, it is impossible to convert $$$A$$$ to $$$B$$$. Why?