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:
def answer(n,A,B):
    A=list(A)
    B=list(B)
    r=n-1
    l=[]
    while A!=B and r>=0:
        if B[r]==A[r]:
            r-=1
        else:
            if B[r]!=A[0]:
                mid=(r+1)//2
                for i in range(0,mid):
                    if A[i]=="0" and A[r-i]=="0":
                        A[r-i]="1"
                        A[i]="1"
                    elif A[i]=="1" and A[r-i]=="1":
                        A[i]="0"
                        A[r-i]="0"
                if (r+1)%2!=0:
                    if A[mid]=="1":
                        A[mid]="0"
                    else:
                        A[mid]="1"

                l.append(r+1)
                r-=1
            else:
                if A[0]=="0":
                    A[0]="1"
                else:
                    A[0]="0"
                l.append(1)
                
    return [len(l)]+l

                    
t=int(input())
for i in range(t):
    n=int(input())
    a=input()
    b=input()
    print(*answer(n,a,b))