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 inp():
    return(int(input()))
def inlt():
    return(list(map(int,input().split())))
def insr():
    s = input()
    return(list(s[:len(s) ]))
def invr():
    return(map(int,input().split()))

n = inp()

for i in range(n):
    m = inp()
    ans = []
    a = insr()
    for p in range(m):
        a[p] = int(a[p])
    b = insr()
    for p in range(m):
        b[p] = int(b[p])

    for j in range(m):
        if(a[j] != b[j]):
            ans.append(j+1)
            tmp = []

            for k in range(j+1):
                a[k] = (a[k] + 1) % 2
            #print(a)
            a[j] = (a[j]+1)%2
            ans.append(1)
            ans.append(j+1)
            tmp = []
            for k in range(j+1):
                a[k] = (a[k] + 1) % 2



            #print(a)
        #a.reverse()

    #print(a)
    #print(ans)
    q = len(ans)

    res = str(q) + " "
    for x in ans:
        res += str(x) + " "

    print(res)