Minimum Deletions to Make String Happy

Given a string s of length n consisting only of the characters 'a' and 'b', your task is to make the string happy by performing the minimum number of deletions. A string is considered happy if there are no two adjacent characters that are the same, i.e. for all indices \( i \) (with \( 1 \leq i < n \)), \( s_i \neq s_{i+1} \).

You need to compute the minimum number of deletions required to achieve this property.

inputFormat

The input is read from stdin and consists of two lines:

1. The first line contains an integer n which represents the length of the string.
2. The second line contains the string s of length n, consisting only of characters 'a' and 'b'.

outputFormat

Output to stdout a single integer, the minimum number of deletions required to make the string happy.

## sample

4
abab

0

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