You are given an string s of length n. And there is a eraser and it deletes neighboring characters of a particular letter when it place on a specific position. For an example 'aaaaba' when we place eraser on 1st 'a'(index 0), string becomes 'ba' (since we deleted all the letters of the neighboring 'a's). Task is to delete the entire string in minimum operations.

Test 1
Input -> 6 aabcbb
Output -> 3

Constraints
1<=n<=1000