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.
from __future__ import division, print_function
# import threading
# threading.stack_size(2**27)
# import sys
# sys.setrecursionlimit(10**7)
# sys.stdin = open('inpy.txt', 'r')
# sys.stdout = open('outpy.txt', 'w')
from sys import stdin, stdout
import bisect            #c++ upperbound
import math
import heapq
i_m=9223372036854775807
def inin():
    return int(input())
def stin():
    return input()
def spin():
    return map(int,stin().split())
def lin():                           #takes array as input
    return list(map(int,stin().split()))
def matrix(n):
    #matrix input
    return [list(map(int,input().split()))for i in range(n)]

################################################
def count2Dmatrix(i,list):
    return sum(c.count(i) for c in list)

def modinv(n,p):
    return pow(n,p-2,p)

def GCD(x, y): 
    x=abs(x)
    y=abs(y)
    if(min(x,y)==0):
        return max(x,y)
    while(y): 
        x, y = y, x % y 
    return x
def Divisors(n) : 
    l = []  
    for i in range(1, int(math.sqrt(n) + 1)) :
        if (n % i == 0) : 
            if (n // i == i) : 
                l.append(i) 
            else : 
                l.append(i)
                l.append(n//i)
    return l
prime=[]
def SieveOfEratosthenes(n): 
    global prime
    prime = [True for i in range(n+1)] 
    p = 2
    while (p * p <= n): 
        if (prime[p] == True): 
            for i in range(p * p, n+1, p): 
                prime[i] = False
        p += 1
    f=[]
    for p in range(2, n): 
        if prime[p]: 
            f.append(p)
    return f
q=[]       
def dfs(n,d,v,c):
    global q
    v[n]=1
    x=d[n]
    q.append(n)
    j=c
    for i in x:
        if i not in v:
            f=dfs(i,d,v,c+1)
            j=max(j,f)
            # print(f)
    return j
# d = {}
 
"""*******************************************************"""
for _ in range(inin()):
    n = inin()
    a = list(stin())
    b = list(stin())
    c = 0

    l = []
    for i in range(n):
        if a[i]!=b[i]:
            l += [i+1, 1, i+1]
            c += 3
    # temp = a
    # l = []
    # i = n-1
    # j = 0
    # while i<n:
    #     # print(a, i)
    #     if a==b:
    #         # print(c)
    #         break
    #     if a[i]!=b[i]:
    #         a = ['1' if a[x] == '0' else '0' for x in range(i+1)][::-1] + a[i+1:]
    #         if a!=temp:
    #             temp = a
    #             l.append(i+1)
    #             # print(a)
    #             # break
    #         else:
    #             i -= 1
    #             l.append(i+1)
    #             a = ['1' if a[x] == '0' else '0' for x in range(i+1)][::-1] + a[i+1:]
    #         c += 1
    #     i -= 1

    #     if i<0:
    #         i = n-1

    #     # print(l)
        
    print(c, *l)
            

    
    
        


    