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:
T = int(input())

def flip(el):
    if el=='1':
        return '0'
    else:
        return '1'
def oper(arr):
    return [flip(el) for el in arr[::-1]]
def solve(a,b):
    ans = ''
    opc = 0
    for i in range(0,n):
        #print(n-i-1,a,b) 
        if a[n-i-1]!=b[n-i-1]:
            #print(n-i-1)
            if a[0]==a[n-i-1]:
                
                ans+=str(n-i) + ' '
                a = oper(a[:n-i])
                opc += 1
            else:
                ans+='1' + ' ' + str(n-i) + ' '
                a = oper(a[:n-i]) 
                opc +=2
        else:
            continue
    return ans,opc 

while T>0:

    n = int(input())

    a = [(el) for el in input()]
    b = [(el) for el in input()]

    
    

    if a!=b:

        ans,opc = solve(a,b)
        
        if n==1:
            print('1 1')
        else:
            print(str(opc) + ' ' + ans)
    
    
    else:
        print(0)

    T-=1