Problem: 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.

Solution (in PYTHON3):

Solution:
def op(x, n):
    return list(reversed([1 - i for i in x[0:n]])) + x[n:]

def go(a, b, ans):
    if len(a) == 0:
        return ans
    if a[-1] == b[-1]:
        return go(a[:-1], b[:-1], ans)
    if a[0] != b[-1]:
        return go(op(a, len(a))[:-1], b[:-1], ans + [len(a)])
    for i in range(len(a) - 2, -1, -1):
        if a[i] != a[0]:
            continue
        a = op(a, i+1)
        a = op(a, len(b))
        x = go(a[:-1], b[:-1], ans + [i+1, len(b)])
        if x is not None:
            return x
    return None

t = int(input())
for _ in range(t):
    n = int(input())
    a = list(map(int, input()))
    b = list(map(int, input()))
    if a != b:
        ans = go(a, b, [])
        print(len(ans), *ans)
    else:
        print(2, len(a), len(a))