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:
######################################################
############Created by Devesh Kumar###################
#############devesh1102@gmail.com####################
##########For CodeForces(Devesh1102)#################
#####################2020#############################
######################################################
import sys
input = sys.stdin.readline
 
# import sys
import heapq 
import copy
import math
import decimal
 
# import sys.stdout.flush as flush
# from decimal import *
#heapq.heapify(li) 
#
#heapq.heappush(li,4) 
#
#heapq.heappop(li)
#
# &    Bitwise AND Operator    10 & 7 = 2
# |    Bitwise OR Operator    10 | 7 = 15
# ^    Bitwise XOR Operator    10 ^ 7 = 13
 
# <<    Bitwise Left Shift operator    10<<2 = 40
# >>    Bitwise Right Shift Operator
# '''############ ---- Input Functions ---- #######Start#####'''
 
 
def inp():
    return(int(input()))
def inlt(): 
    return(list(map(int,input().split())))
def insr():
    s = input()
    return(list(s[:len(s) - 1]))
def insr2():
    s = input()
    return((s[:len(s) - 1]))
def invr():
    return(map(int,input().split()))
############ ---- Input Functions ---- #######End
# #####   
 
 
 

def pr_list(a):
    print(*a, sep=" ")
def main():
    tests =  inp()
    # tests = 1
    mod = 1000000007
    limit = 10**18
    ans = 0
    stack = []
    hashm = {}
    arr = []
    heapq.heapify(arr) 

    for test in range(tests):
        n = inp()
        a= insr()

        b = insr()
        for i in range(n):
            a[i] = int(a[i])
        for i in range(n):
            b[i] = int(b[i])
        ans = []
        def rotate(l,r,arr):
            dum = []
            for i in range(r,l-1,-1):
                dum.append( not(arr[i]))
            arr[l:r+1] = dum
            return arr
            
        for i in range(n-1,-1,-1):
            if a[i] != b[i]:
                if a[0] != a[i]:
                    ans.append(1)
                    a[0] = not(a[0])
                ans.append(i+1)
                a  = rotate(0,i,a)
        ans = [len(ans)] + ans
        pr_list(ans)

if __name__== "__main__":
    main()