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
input = sys.stdin.readline
def print(val):
    sys.stdout.write(str(val) + ' ')
def prog():
    for _ in range(int(input())):
        n = int(input())
        a = input().strip() + '0'
        b = input().strip() + '0'
        if a == b:
            print(0)
            sys.stdout.write('\n')
        else:
            loca = []
            locb = []
            start = False
            last = 0
            for i in range(n+1):
                if a[i] == '1':
                    if start == False:
                        start = True
                        last = i
                elif start:
                    start = False
                    loca.append([last,i-1])
            start = False
            last = 0
            for i in range(n+1):
                if b[i] == '1':
                    if start == False:
                        start = True
                        last = i
                elif start:
                    start = False
                    locb.append([last,i-1])
            locb = locb[::-1]
            amount = 2*(len(loca)) + 2*len(locb)
            if (len(loca)):
                amount -= (loca[0][0] == 0)
            if (len(locb)):
                amount -= (locb[-1][0] == 0)
            print(amount)
            for L,R in loca:
                if (L > 0):
                    print(L)
                print(R+1)
            for L, R in locb:
                print(R+1)
                if (L > 0):
                    print(L)
            sys.stdout.write('\n')
prog()