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
# sys.setrecursionlimit(10**6) 
input=sys.stdin.readline
t=int(input())
for t1 in range(t):
    n=int(input())
    a1=input()
    a1=a1.strip()
    b1=input()
    b1=b1.strip()
    c=0
    a=[]
    b=[]
    for i in range(n):
        a.append(int(a1[i]))
        b.append(int(b1[i]))
    ans=[]
    for i in range(n-1,-1,-1):
        # print(a,i)
        if(a[i]!=b[i]):
            if(a[0]!=b[i]):
                # print(i)
                for j in range(i+1):
                    a[j]=a[j]^1
                # print(a)
                a=a[:i+1][::-1]+a[i+1:]
                ans.append(i+1)
            else:
                a[0]=b[i]^1
                # print(a[0])
                for j in range(i+1):
                    a[j]=a[j]^1
                # print(a)
                z=a[:i+1]
                z=z[::-1]
                a=z+a[i+1:]
                ans.append(1)
                ans.append(i+1)
              
                # print(a)
                # break
        # print(a)
    s=""
    for i in ans:
        s+=str(i)+" "
    # a11=[]
    # for i in a:
    #     a11.append(i)

    # for i in ans:
    #     z=[]
    #     for j in range(i):
    #         z.append(a11[j])
    #     z2=[]
    #     for j in range(i,n):
    #         z2.append(a11[j])
    #     # z2=a1[i:]
    #     # print(z,z2)
    #     for j in range(len(z)):
    #         z[j]=int(z[j])^1
    #     z=z[::-1]
    #     a11=z+z2
    #     print(i,a11)
    # print(a11,"lol")
    print(len(ans),s)