Solve the programming task below in a Python markdown code block.
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 ------ 

$1 ≤ T ≤ 100$
$1 ≤ N ≤ 10^{5}$
- 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 1 ------ 
Test Case $1$: String can be transferred through following operations: send $1$ copy of character $\texttt{c}$, send $1$ copy of character $\texttt{b}$, send $1$ copy of character $\texttt{c}$, send $1$ copy of character $\texttt{d}$, and send $1$ copy of character $\texttt{c}$. Thus, total $5$ operations are required. 

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