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 sys,math,collections
from collections import defaultdict

#from itertools import permutations,combinations
	
def file():
	sys.stdin = open('input.py', 'r')
	sys.stdout = open('output.py', 'w') 
def get_array():
	l=list(map(int, input().split()))
	return l
def get_2_ints():	
	a,b=map(int, input().split())
	return a,b
def get_3_ints():	
	a,b,c=map(int, input().split())
	return a,b,c	
def sod(n):
	n,c=str(n),0
	for i in n:	
		c+=int(i)
	return c	

def getFloor(A, x):

	(left, right) = (0, len(A) - 1)

	floor = -1
	while left <= right:
		mid = (left + right) // 2
		if A[mid] == x:
			return A[mid]
		elif x < A[mid]:
			right = mid - 1
		else:
			floor = A[mid]
			left = mid + 1
			
	return floor
#file()
def main():
	for tt in range(int(input())):
		n=int(input())
		l1=list(input())
		l2=list(input())
		ans=[]
		for i in range(n-1,-1,-1):
			#print(i)
			#print(l1)
			#print(l2)
			if(i==0):
				if(l1[i]!=l2[i]):
					ans.append(1)
			else:
			    if(l1[i]!=l2[i]):
			        if(l1[i]==l1[0]):
			            temp=l1[:i+1]
			            for j in range(len(temp)):
			            		if(temp[j]=='1'):
			            			temp[j]='0'
			            		else:
			            		    temp[j]='1'
			            temp.reverse()		    
			            l1=temp[:]+l1[i+1:]

			            ans.append(i+1)
			        else:
			        	if(l1[0]=='1'):
			        		l1[0]='0'
			        	else:
			        	    l1[0]='1'	
			        	ans.append(1)    
			        	temp=l1[:i+1]
			        	#print("TEMP:",temp) 
			        	for j in range(len(temp)):
			        		if(temp[j]=='1'):
			        			#print("dhh")
			        			temp[j]='0'
			        		else:
			        			temp[j]='1'
			        	
			        	temp.reverse()
			        	#print("TEMP:",temp)		
			        	l1=temp[:]+l1[i+1:]
			        	ans.append(i+1)
		if(len(ans)==0):
			print(0)
		else:
			print(len(ans),*ans)	            

			                


































				

			







            
			
































		








if __name__ == '__main__':
    main()