You are given a string $s$ of even length $n$. String $s$ is binary, in other words, consists only of 0's and 1's.

String $s$ has exactly $\frac{n}{2}$ zeroes and $\frac{n}{2}$ ones ($n$ is even).

In one operation you can reverse any substring of $s$. A substring of a string is a contiguous subsequence of that string.

What is the minimum number of operations you need to make string $s$ alternating? A string is alternating if $s_i \neq s_{i + 1}$ for all $i$. There are two types of alternating strings in general: 01010101... or 10101010...


-----Input-----

The first line contains a single integer $t$ ($1 \le t \le 1000$) — the number of test cases.

The first line of each test case contains a single integer $n$ ($2 \le n \le 10^5$; $n$ is even) — the length of string $s$.

The second line of each test case contains a binary string $s$ of length $n$ ($s_i \in$ {0, 1}). String $s$ has exactly $\frac{n}{2}$ zeroes and $\frac{n}{2}$ ones.

It's guaranteed that the total sum of $n$ over test cases doesn't exceed $10^5$.


-----Output-----

For each test case, print the minimum number of operations to make $s$ alternating.


-----Example-----
Input
3
2
10
4
0110
8
11101000

Output
0
1
2



-----Note-----

In the first test case, string 10 is already alternating.

In the second test case, we can, for example, reverse the last two elements of $s$ and get: 0110 $\rightarrow$ 0101.

In the third test case, we can, for example, make the following two operations:   11101000 $\rightarrow$ 10101100;  10101100 $\rightarrow$ 10101010.

```python

USER_FILENAME = "<user_code>"
import sys, json, builtins
import math, heapq, bisect, itertools, functools, collections, statistics, fractions, decimal, operator, array, random, re, string, os, pathlib
try:
    import resource as _res
except Exception:
    _res = None
from collections import Counter, defaultdict, deque, OrderedDict
from functools import lru_cache, reduce
from itertools import accumulate, permutations, combinations, product
from math import gcd, ceil, floor, sqrt
from decimal import Decimal
try:
    from typing import *
except Exception:
    pass
try:
    sys.setrecursionlimit(1_000_000)
except Exception:
    pass
try:
    import site as _site
    try:
        _sys_sites = _site.getsitepackages() if hasattr(_site, "getsitepackages") else []
        for _p in _sys_sites:
            if _p and _p not in sys.path:
                sys.path.append(_p)
    except Exception:
        pass
    try:
        _usp = _site.getusersitepackages()
        if isinstance(_usp, str):
            _usp = [_usp]
        for _p in _usp:
            if _p and _p not in sys.path:
                sys.path.append(_p)
    except Exception:
        pass
except Exception:
    pass

ns = {"__name__": "__main__"}
for _k, _v in list(globals().items()):
    if not _k.startswith("_"):
        ns[_k] = _v
_CODE = "import collections\nimport math\nfrom itertools import permutations as p\n\nfor t in range(int(input())):\n    n=int(input())\n    s=input()\n    stack=[]\n    for i in s:\n        if i=='1':\n            if stack and stack[-1]=='0':\n                stack.pop()\n        else:\n            if stack and stack[-1]=='1':\n                stack.pop()\n        stack.append(i)\n    print(len(stack)//2)"
_co = compile(_CODE, USER_FILENAME, "exec")
exec(_co, ns, ns)

```

Measured memory_bytes: 13123