Crazy Typist

David is an avid typist. Unfortunately with how fast he moves his fingers he can often type duplicate characters by mistake. Given a string \(s\) of length \(n\) find the string david meant to type. It is safe to assume that any duplicate character is a mistake

Input Specification

The first line contains one integer \(n\)
The next line will contain a string of \(n\) characters

Output Specification

Output the correct string on a single line

Bounds

\(1 \leq n \leq 10^6\) all characters are lowercase alphabet characters (i.e. a-z)

Sample Input

10
aaabbaaaac

Sample Output

abac