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:
#########################################################################################################\
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###################################The_Apurv_Rathore#####################################################
#########################################################################################################
#########################################################################################################

import sys,os,io
from math import log, gcd, ceil
from collections import defaultdict, deque, Counter
from heapq import heappush, heappop


import math 



def ncr(n, r, p):  #using fermat's little theorem
    num = den = 1
    for i in range(r):
        num = (num * (n - i)) % p
        den = (den * (i + 1)) % p
    return (num * pow(den,
                      p - 2, p)) % p

  
def primeFactors(n): 
    l = []
    while n % 2 == 0: 
        l.append(2)
        n = n / 2
          
    for i in range(3,int(math.sqrt(n))+1,2): 
          

        while n % i== 0: 
            l.append(int(i))
            n = n / i 
    if n > 2: 
        l.append(n)
    return list(set(l))
    
def power(x, y, p) : 
	res = 1
	x = x % p 
	if (x == 0) : 
		return 0
	while (y > 0) : 
		if ((y & 1) == 1) : 
			res = (res * x) % p 
		y = y >> 1	 # y = y/2 
		x = (x * x) % p 		
	return res 


def si():
    return input()

# input = io.BytesIO(os.read(0, os.fstat(0).st_size)).readline

def prefix_sum(arr):
    r = [0] * (len(arr)+1)
    for i, el in enumerate(arr):
        r[i+1] = r[i] + el
    return r

def divideCeil(n,x):
    if (n%x==0):
        return n//x
    return n//x+1

def ii():
    return int(input())

def li():
    return list(map(int,input().split()))

def ws(s): sys.stdout.write(s + '\n')
def wi(n): sys.stdout.write(str(n) + '\n')
def wia(a): sys.stdout.write(' '.join([str(x) for x in a]) + '\n')


if(os.path.exists('input.txt')):
    sys.stdin = open("input.txt","r")
    sys.stdout = open("output.txt","w")
t = 1
t = int(input())
for _ in range(t):
    n = ii()
    a = list(si())  
    b = list(si())
    i = 0
    j = n-1
    ptr = n-1
    rev=0
    ans = []
    while(i<=j and ptr>=0):
        if (rev==0):
            if (b[ptr]==a[i]):
                ans.append(1)
                rev = 1
                ans.append(ptr+1)
                ptr-=1
                i+=1
            else:
                rev = 1
                ans.append(ptr+1)
                ptr-=1
                i+=1
        else:
            if (b[ptr]!=a[j]):
                ans.append(1)
                rev = 0
                ans.append(ptr+1)
                ptr-=1
                j-=1
            else:
                rev = 0
                ans.append(ptr+1)
                ptr-=1
                j-=1
    print(len(ans),*ans)