This is the easy version of the problem. The difference between the versions is the constraint on n and the required number of operations. You can make hacks only if all versions of the problem are solved.

There are two binary strings a and b of length n (a binary string is a string consisting of symbols 0 and 1). In an operation, you select a prefix of a, and simultaneously invert the bits in the prefix (0 changes to 1 and 1 changes to 0) and reverse the order of the bits in the prefix.

For example, if a=001011 and you select the prefix of length 3, it becomes 011011. Then if you select the entire string, it becomes 001001.

Your task is to transform the string a into b in at most 3n operations. It can be proved that it is always possible.

Input

The first line contains a single integer t (1≤ t≤ 1000) — the number of test cases. Next 3t lines contain descriptions of test cases.

The first line of each test case contains a single integer n (1≤ n≤ 1000) — the length of the binary strings.

The next two lines contain two binary strings a and b of length n.

It is guaranteed that the sum of n across all test cases does not exceed 1000.

Output

For each test case, output an integer k (0≤ k≤ 3n), followed by k integers p_1,…,p_k (1≤ p_i≤ n). Here k is the number of operations you use and p_i is the length of the prefix you flip in the i-th operation.

Example

Input


5
2
01
10
5
01011
11100
2
01
01
10
0110011011
1000110100
1
0
1


Output


3 1 2 1
6 5 2 5 3 1 2
0
9 4 1 2 10 4 1 2 1 5
1 1

Note

In the first test case, we have 01→ 11→ 00→ 10.

In the second test case, we have 01011→ 00101→ 11101→ 01000→ 10100→ 00100→ 11100.

In the third test case, the strings are already the same. Another solution is to flip the prefix of length 2, which will leave a unchanged.
from sys import stdin
from bisect import bisect_left as bl
from bisect import bisect_right as br

def input():
    return stdin.readline()[:-1]


def intput():
    return int(input())


def sinput():
    return input().split()


def intsput():
    return map(int, sinput())


class RangedList:
    def __init__(self, start, stop, val=0):
        self.shift = 0 - start
        self.start = start
        self.stop = stop
        self.list = [val] * (stop - start)

    def __setitem__(self, key, value):
        self.list[key + self.shift] = value

    def __getitem__(self, key):
        return self.list[key + self.shift]

    def __repr__(self):
        return str(self.list)

    def __iter__(self):
        return iter(self.list)


def dprint(*args, **kwargs):
    if debugging:
        print(*args, **kwargs)


debugging = 1
# Code
t = intput()
for _ in range(t):
    n = intput()
    a = list(map(int, input()))
    b = list(map(int, input()))

    operations = []
    cnt = 1
    for i in range(len(a) - 1, -1, -1):
        if cnt % 2:
            flip = False
        else:
            flip = True
        l = i + 1
        if cnt % 2:
            r = (cnt + 1) // 2 - 1
        else:
            r = n - cnt // 2

        val = a[r]
        if flip:
            val = (val + 1) % 2
        if val != b[i]:
            pass
        else:
            operations.append(1)
        operations.append(l)
        cnt += 1
    print(len(operations), *operations)
                

