Taco: Palindrome Rearrangement Checker

You are given an integer n and a string s of length n. Your task is to determine whether the characters of the string can be rearranged to form a palindrome under the special condition that each character must appear an even number of times.

If it is possible to rearrange s so that every character has an even frequency, output YES; otherwise, output NO.

The input begins with an integer T denoting the number of test cases. Each test case consists of a line containing an integer n and the string s separated by a space. For each test case, you should print the answer on a new line.

inputFormat

The first line of input contains a single integer T (the number of test cases). Each of the following T lines contains a test case in the following format:

n s

Here, n is the length of the string and s is a string consisting of characters. It is guaranteed that the length of s is exactly n.

outputFormat

For each test case, output a single line with either YES if the string can be rearranged so that every character appears an even number of times, or NO otherwise.

## sample

3
4 abba
6 aabbcc
4 abcd

YES
YES
NO

</p>