# 011011010011.

Information has emerged that this encoding has been deciphered, as a result of which the agent will have to use a backup encoding. In it, the letter A is replaced by 21, the letter B by 122, and the letter V by 1. What code will this message receive in the new encoding?
Answer: 211221121.

Solution. Let's look at the right end of the code. Two ones at the end can only come from the letter A: 011011010011.

Next, we look at the rightmost digit of those we haven't figured out yet, from which letter it came. The digit 0 at the end is only present in B: 011011010011.

Similarly, the previous letter is also B: 011011010011.

Now the "undeciphered" rightmost digit is 1. Before it stands a 0. This can only come from the letter B: 011011010011.

The "undeciphered" digits on the right are two ones. This can only come from A:

The message obtained is ABBBA, which when encoded anew gives 211221121.

A B BB A