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.
from collections import Counter
import string
import math
import sys
# sys.setrecursionlimit(10**6) 
from fractions import Fraction
def array_int():
    return [int(i) for i in sys.stdin.readline().split()]
def vary(arrber_of_variables):
    if arrber_of_variables==1:
        return int(sys.stdin.readline())
    if arrber_of_variables>=2:
        return map(int,sys.stdin.readline().split()) 
def makedict(var):
    return dict(Counter(var))
testcases=vary(1)
for _ in range(testcases):
    n=vary(1)
    a=list(input())
    b=list(input())
    ans=0
    lengths=[]
    for i in range(n):
        if a[n-1-i]!=b[n-1-i]:
            if a[0]!=b[n-1-i]:
                ans+=1
                lengths.append(n-i)
                for j in range((n-i)//2):
                    a[j],a[n-1-i-j]=a[n-1-i-j],a[j]
                for j in range(n-i):
                    a[j]=str(int(a[j])^1)
                # print(a)
            else:
                ans+=1
                lengths.append(1)
                a[0]=str(int(a[0])^1)
                ans+=1
                lengths.append(n-i)
                for j in range((n-i)//2):
                    a[j],a[n-1-i-j]=a[n-1-i-j],a[j]
                for j in range(n-i):
                    a[j]=str(int(a[j])^1)
                # print(a)
    # print(a)
    print(ans,*lengths)
