Given a string seq consisting of the characters $\text{'}$A$\text{'}$ and $\text{'}$B$\text{'}$ only, in one move, you can delete either an $"$AB$"$ or a $"$BB$"$ substring. After a move, the remaining parts of the string get concatenated. Find the minimum possible length of the remaining string after performing any number of moves. Note: A substring is a contiguous subsequence of a string. Example seq $=$ "BABBA" Using $0-$based indexing, the following moves are optimal. $.$ Delete the substring $"$AB$"$ starting at index $1.$ "BABBA" $-$ "BBA" $.$ Delete the substring $"$BB$"$ starting at index $0.$ "BBA" $-"$A$"$