We are given a string S of length N$,$ consisting only of letters $\text{'}$A$\text{'}$ and$/$or $\text{'}$B$\text{'}.$ Our goal is to obtain a string

in a format $"$A$..$AB$..$B$"($all letters $\text{'}$A$\text{'}$ occur before all letters $\text{'}$B$\text{'})$ by deleting some letters from S$.$

In particular, strings consisting only of letters $\text{'}$A$\text{'}$ or only of letters $\text{'}$B$\text{'}$ fit this format

Write a function

int solution$($String S$)$

that given a string S$,$ return the minimum number of letters that need to be deleted from S in order to obtain a

string in the above format.

Example

$1$ Given S $=$ "BAAABAB", the function should return $2.$ We can obtain "AAABB" by deleting the occurrence of $\text{'}$B$\text{'}$ and

the last occurrance of $\text{'}$A$\text{'}$

$2.$ Given S $=$ "BBABAA", the function should return $3,$ we can delete all occurrence of $"$A$"$ or all occurrence of $"$B$".$

$3.$ Given S $=$ "AABBBB", the function should return $0$

$,$ we do not have to delete any letters because the given string is already in the format.

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