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:
from sys import stdin,stdout
input = stdin.readline
def write(n,sep="\n"):
    stdout.write(str(n))
def gil():
    return list(map(int, input().split()))

def rv(a,p):
    x = a[:p+1]
    for i in range(p+1):
        x[i] = 1 - x[i]
    return x[::-1] + a[p+1:]

for _t in range(int(input())):
    n = int(input())
    a = list(map(int,list(input().strip()))) + [0]
    b = list(map(int,list(input().strip()))) + [0]
    o = []
    o2 = []
    for i in range(1,n+1):
        #print(a,i)
        if a[i-1] != a[i]:
            o.append(i)
        if b[i-1] != b[i]:
            o2.append(i)
    #print(a)

    o = o + o2[::-1]
    write(len(o))
    write(" ")
    for i in o:
        write(i)
        write(" ")
    write('\n')