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:
import sys
inp=sys.stdin.readline

def linp(x):
    return list(map(int,x.split()))
def minp(x):
    return map(int,x.split())
from functools import *
def main():
    for _ in range(int(inp())):
        n=int(inp())
        a=input();a=list(a);a=list(map(int,a))
        b=input();b=list(b);b=list(map(int,b))
        a_ind=0
        b_ind=n-1
        ans=[]
        while a != b:
            if a[b_ind]==b[b_ind]:
                b_ind-=1
            elif a[b_ind]!=b[b_ind]:
                if a[0]!=b[b_ind]:
                    ans.append(b_ind+1)
                    temp=a[:b_ind+1]
                    a=temp[::-1]+a[b_ind+1:]
                    for i in range(b_ind+1):
                        if a[i]==0:
                            a[i]=1
                        else:
                            a[i]=0
                    if a==b:
                        break
                    b_ind-=1
                else:
                    if a[0]==1:
                        a[0]=0
                    else:
                        a[0]=1
                    ans.append(1)
        print(len(ans),*ans)
main()
# 1
# 2
# 01
# 10