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.
import os
import sys
from io import BytesIO, IOBase

def operation (A, pos): 
    for i in range (pos+1): 
        if A[i] == 1: A[i]=0 
        else: A[i]=1 
    
    i,j = 0,pos 
    while i<j: 
        A[i],A[j] = A[j],A[i] 
        i += 1 
        j -= 1 

def main(): 
    t = int(input()) 
    for _ in range (t): 

        n = int(input()) 
        a = input() 
        b = input() 
        A = list() 
        B = list() 
        for i in range(n): 
            A.append(int(a[i])) 
            B.append(int(b[i])) 
        
        k=0 
        p=list() 
        for i in range (n-1, 0, -1): 
            if A[i] != B[i]: 
                if A[0] != B[i]: 
                    k+=1 
                    p.append (i+1) 
                    operation (A, i) 
                else: 
                    k+=2 
                    if A[0]==0: 
                        A[0]=1
                    else: 
                        A[0]=0 
                    p.append (1) 
                    p.append (i+1) 
                    operation (A, i) 
        
        if A[0] != B[0]: 
            A[0] = B[0] 
            k += 1
            p.append(1)
        
        print (k, end=" ") 
        for prefix in p: 
            print (prefix, end=" ") 
        print() 

# region fastio
BUFSIZE = 8192
class FastIO(IOBase):
    newlines = 0

    def __init__(self, file):
        self._fd = file.fileno()
        self.buffer = BytesIO()
        self.writable = "x" in file.mode or "r" not in file.mode
        self.write = lambda s: self.buffer.write(s.encode()) if self.writable else None

    def read(self):
        if self.buffer.tell():
            return self.buffer.read().decode("ascii")
        return os.read(self._fd, os.fstat(self._fd).st_size).decode("ascii")

    def readline(self):
        while self.newlines == 0:
            b = os.read(self._fd, max(os.fstat(self._fd).st_size, BUFSIZE))
            self.newlines = b.count(b"\n") + (not b)
            ptr = self.buffer.tell()
            self.buffer.seek(0, 2), self.buffer.write(b), self.buffer.seek(ptr)
        self.newlines -= 1
        return self.buffer.readline().decode("ascii")

    def flush(self):
        if self.writable:
            os.write(self._fd, self.buffer.getvalue())
            self.buffer.truncate(0), self.buffer.seek(0)


def print(*args, sep=" ", end="\n", file=sys.stdout, flush=False):
    at_start = True
    for x in args:
        if not at_start:
            file.write(sep)
        file.write(str(x))
        at_start = False
    file.write(end)
    if flush:
        file.flush()

sys.stdin, sys.stdout = FastIO(sys.stdin), FastIO(sys.stdout)
input = lambda: sys.stdin.readline().rstrip("\r\n")

# endregion
sys.setrecursionlimit(10000)
if __name__ == "__main__":
    main()