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:
import sys
import os,io

input = sys.stdin.readline
# input_all = sys.stdin.read
# input = io.BytesIO(os.read(0,os.fstat(0).st_size)).readline
# input_all = io.BytesIO(os.read(0,os.fstat(0).st_size)).read
def read_int():
	return map(int, input().split())
def read_list():
	return list(map(int, input().split()))
def print_list(l):
	print(' '.join(map(str,l)))
# import heapq as hq
# import bisect as bs
# from collections import deque as dq
# from collections import defaultdict as dc 
# import math

# f = open('test.py')
# input = f.readline
# input_all = f.read


N = int(input())
for i in range(N):
	n = int(input())
	a = input().strip()
	b = input().strip()
	res = []
	rev = False
	start,end = 0,n-1
	for i in range(n-1,-1,-1):
		if not rev:
			if b[i]==a[end]:
				end-=1
			else:
				if b[i]==a[start]:
					res.append(1)
				res.append(i+1)
				start+=1
				rev = not rev
		else:
			if b[i]!=a[start]:
				start+=1
			else:
				if b[i]!=a[end]:
					res.append(1)
				res.append(i+1)
				end-=1
				rev = not rev

		# print(a)
	print_list([len(res)]+res)