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 PYTHON):

Solution:
import atexit
import io
import sys
import math
_INPUT_LINES = sys.stdin.read().splitlines()
input = iter(_INPUT_LINES).next
_OUTPUT_BUFFER = io.BytesIO()
sys.stdout = _OUTPUT_BUFFER
@atexit.register
def write():
    sys.__stdout__.write(_OUTPUT_BUFFER.getvalue())
def dist(a,b):
    return abs(a[0]-b[0])+abs(a[1]-b[1]) 
def takla():
    for _ in range(int(input())):
      n=int(input())
      a=input()
      b=input()
      reverse = False
      i=0
      k=n-1
      moves=[]
      j=n-1
      while j>=0:
          
        if not reverse:
          if a[i]==b[j]:
            moves.append(1)
            moves.append(abs(j)+1)
            i+=1
            i,k=k,i
            reverse = True
          else:
            moves.append(abs(j)+1)
            i+=1
            i,k=k,i
            reverse = True
        else:
          if a[i]!=b[j]:
            moves.append(1)
            moves.append(abs(j)+1)
            i-=1
            i,k=k,i
            reverse = False
          else:
            moves.append(abs(j)+1)
            i-=1
            i,k=k,i
            reverse = False
        j-=1
      print len(moves),
      for i in moves:
        print i,
      print



        
if __name__ == "__main__":
	  takla()