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.
import string
def fun(s,n):#invert plus reverse
    ans = ''
    for i in range(n):
        w = int(s[i])
        ans = str(abs(w-1)) + ans
    return list(ans)

def solve(a,ans):
    j = -1
    while(j>=0):
        j = -1
        for i in range(n-1,-1,-1):
            if a[i]=='1':
                j = i
                break
        if a[0]=='0':
            ans.append(1)
            a[0] = 1
        ans.append(j)
    return ans
t = int(input())
for _ in range(t):
    n = int(input())
    a = input()
    b = input()
    if a==b:
        print(0)
        continue
    a = list(a)
    b = list(b)
    ans = []
    n1 = n
    j = n-1
    while(a.count('1')!=0):
#        print(a,'a')
#        print(j,'j')
        for i in range(len(a)-1,-1,-1):
            if a[i]=='1':
#                print(i)
                j = i
                break
        if a[0]=='0':
            a[0]=1
            ans.append(1)
#            print(a,'a')
        ans.append(j+1)
        a = fun(a,j+1)
    ans1  = ans[:]
    
    
    n = n1
    a = b[:]
    j = n-1
    ans = []
#    print(a)
    while(a.count('1')!=0):
#        print(a,'a')
#        print(j,'j')
        for i in range(len(a)-1,-1,-1):
            if a[i]=='1':
#                print(i)
                j = i
                break
        if a[0]=='0':
            a[0]=1
            ans.append(1)
#            print(a,'a')
        ans.append(j+1)
        a = fun(a,j+1)
#    print(ans)
#    print(ans)
#    print(ans1)
    
    ans.reverse()
    x = len(ans1+ans)
    print(x,*(ans1+ans))
#    print(solve(a,ans))
    