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:
from sys import stdout
from sys import stdin
def get():
    return stdin.readline().strip()
def getf():
    return [int(i) for i in get().split()]
def put(a, end = "\n"):
    stdout.write(str(a) + end)
def putf(a, sep = " ", end = "\n"):
    stdout.write(sep.join(map(str, a)) + end)

def pin():
    res = ""
    a = stdin.read(1)
    while(a not in {" ", "\n"}):
        res += a
        a = stdin.read(1)
    return res

def do(s, x):
    for i in range(x + 1):
        s[i] = (s[i] + 1)%2
    s = s[:i + 1][::-1] + s[i + 1:]
    return s
def solve(n, a, b):
    ans = [0]
    for i in range(n - 1, -1, -1):
        if(a[i] != b[i]):
            if(a[0] != b[i]):
                a = do(a, i)
                ans += [i + 1]
                ans[0] += 1
            else:
                a[0] = (a[0] + 1)%2
                a = do(a, i)
                ans += [1, i + 1]
                ans[0] += 2
    return ans
def main():
    t = int(pin())
    for i in range(t):
        n = int(pin())
        a = [int(i) for i in pin()]
        b = [int(i) for i in pin()]
        putf(solve(n, a, b))
main()