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, stdout
from sys import maxsize
input = stdin.readline
# def print(n):
#    stdout.write(str(n)+'\n')


def solve():
    pass


def update(a, i):
    for j in range(i+1):
        a[j] = 1-a[j]
    for j in range(i//2+1):
        a[j], a[i-j] = a[i-j], a[j]


test = 1
test = int(input().strip())
for t in range(0, test):
    n = int(input().strip())
    # String Input, converted to mutable list.
    s1 = list(input().strip())
    # String
    s2 = list(input().strip())
    a = [int(x) for x in s1]
    b = [int(x) for x in s2]
    ans = []
    temp = a[0]
    for i in range(n-1, -1, -1):
        if(a[i] != b[i]):
            if(temp != b[i]):
                ans.append(i+1)
                update(a, i)
                temp = b[i]
            else:
                ans.append(1)
                a[0] = 1-a[0]
                ans.append(i+1)
                update(a, i)
                temp = b[i]
    print(len(ans), end=' ')

    def onedarr(a):
        for el in a:
            print(el, end=' ')
        print()
    onedarr(ans)
    # n, k = list(map(int, input().strip().split()))
    # arr = [int(x) for x in input().strip().split()]
    # brr = [list(map(int,input().strip().split())) for i in range(rows)]              # 2D array row-wise input
    ans = solve()


'''
rows, cols = (5, 5)
arr = [[0]*cols for j in range(rows)]                                         # 2D array initialization
rev_str=s[::-1]                                                               # To reverse given string
b=input().strip().split()                                                     # list created by spliting about spaces
brr = [[int(b[cols*i+j]) for j in range(cols)] for i in range(rows)]          # 2D array Linear Input
rows,cols=len(brr),len(brr[0])                                                # no of rows/cols for 2D array
arr.sort(key = lambda x : x[1])                                               # sort list of tuples by 2nd element, Default priority - 1st Element then 2nd Element
s=set()                                                                       # empty set
a=maxsize                                                                     # initializing infinity
b=-maxsize                                                                    # initializing -infinity
mapped=list(map(function,input))                                              # to apply function to list element-wise
try:                                                                          # Error handling
    #code 1
except:                                                                       # ex. to stop at EOF
    #code 2 , if error occurs
'''
