String protocol ~ Multiplex Coder

An input string

$S$ of length $N$ is transferred through the network using a special protocol. The protocol can send the string through a series of operations. In one operation, we can choose a lowercase english alphabet $C$ and do one of the following:

Transfer $1$ copy of $C$ through the network.
Transfer $2$ copies of $C$ through the network.

Each of the above transfers take $1$ unit of time.

Find the minimum time in which we can transfer the entire string $S$ through the network.

Input Format

The first line will contain $T$ - the number of test cases. Then the test cases follow.
First line of each test case contains $N$ - the length of the string $S$ .
Second line of each test case contains the string $S$ .

Output Format

For each test case, output in a single line, the minimum time required to transfer the string.

Constraints

$1 \leq T \leq 100$
$1 \leq N \leq 10^{5}$
Sum of $N$ over all test cases does not exceed $10^{5}$ .
String $S$ contains lowercase english alphabets only.

Sample Input 1

2
5
cbcdc
6
aabeee

Sample Output 1

5
4

Explanation

Test Case $1$ : String can be transferred through following operations: send $1$ copy of character $c$ , send $1$ copy of character $b$ , send $1$ copy of character $c$ , send $1$ copy of character $d$ , and send $1$ copy of character $c$ . Thus, total $5$ operations are required.

Test Case $2$ : String can be transferred through following operations: send $2$ copies of character $a$ , send $1$ copy of character $b$ , send $1$ copy of character $e$ , and send $2$ copies of character $e$ . Thus, total $4$ operations are required.

String protocol