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 stdin, stdout, setrecursionlimit
#import threading

# tail-recursion optimization
# In case of tail-recusion optimized code, have to use python compiler.
# Otherwise, memory limit may exceed.
# declare the class Tail_Recursion_Optimization
class Tail_Recursion_Optimization:
    def __init__(self, RECURSION_LIMIT, STACK_SIZE):
        setrecursionlimit(RECURSION_LIMIT)
        threading.stack_size(STACK_SIZE)
        return None
        
class SOLVE:
    def solve(self):
        R = stdin.readline
        #f = open('input.txt');R = f.readline
        W = stdout.write
        
        ans = []
        
        for i in range(int(R())):
            n = int(R())
            a = R()[:-1]
            b = R()[:-1]
            
            cnt = 0
            s   = ''
            for j in range(n):
                if a[j] != b[j]:
                    s   += str(j+1) + ' ' + '1' + ' ' + str(j+1) + ' '
                    cnt += 3
            ans.append(str(cnt) + ' ' + s)
        
        W('\n'.join(ans))
        return 0
        
def main():
    s = SOLVE()
    s.solve()
#Tail_Recursion_Optimization(10**7, 100*1024**2) # recursion-call size, stack-size in byte (MB*1024**2)
#threading.Thread(target=main).start()
main()