Question
String Shift
Zara holds a string T of length M. In one move, she can transform T into a string B of length M-1 by setting each Bi (1 ≤ i < M) to either Ti or Ti+1.
She must repeat this until all characters in the resulting string are identical.
Find the minimum number of moves needed.
Input
The first line of the input contains a single integer M.
The second line of the input contains a string T of length M.

Constraints
1 ≤ N ≤ 100
All the characters in T are lowercase english letters.
Output
Print the minimum number of moves required so that string T has all the same characters.
Example
Sample Input
6
packat
Sample Output
2
Explaination
packat -> aakaa -> aaaa

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