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:
#pyrival orz
import os
import sys
import math
from io import BytesIO, IOBase


input = sys.stdin.readline
############ ---- Input Functions ---- ############
def inp():
    return(int(input()))
def inlt():
    return(list(map(int,input().split())))
def insr():
    s = input()
    return(list(s[:len(s) - 1]))
def invr():
    return(map(int,input().split()))

############ ---- Dijkstra with path ---- ############
def dijkstra(start, distance, path, n):
    # requires n == number of vertices in graph,
    # adj == adjacency list with weight of graph

    visited = [False for _ in range(n)]  # To keep track of vertices that are visited
    distance[start] = 0  # distance of start node from itself is 0

    for i in range(n):
        v = -1  # Initialize v == vertex from which its neighboring vertices' distance will be calculated
        for j in range(n):
            # If it has not been visited and has the lowest distance from start
            if not visited[v] and (v == -1 or distance[j] < distance[v]):
                v = j

        if distance[v] == math.inf:
            break

        visited[v] = True  # Mark as visited

        for edge in adj[v]:
            destination = edge[0]  # Neighbor of the vertex
            weight = edge[1]  # Its corresponding weight

            if distance[v] + weight < distance[destination]:  # If its distance is less than the stored distance
                distance[destination] = distance[v] + weight  # Update the distance
                path[destination] = v  # Update the path
        

def gcd(a, b):
    if b == 0:
        return a
    else:
        return gcd(b, a%b)

def lcm(a, b):
    return (a*b)//gcd(a, b)

def ncr(n, r):
    return math.factorial(n)//(math.factorial(n-r)*math.factorial(r))

def npr(n, r):
    return math.factorial(n)//math.factorial(n-r)

def seive(n):
    primes = [True]*(n+1)
    ans = []

    for i in range(2, n):
        if not primes[i]:
            continue

        j = 2*i
        while j <= n:
            primes[j] = False
            j += i

    for p in range(2, n+1):
        if primes[p]:
            ans += [p]

    return ans

def factors(n):
    factors = []

    x = 1
    while x*x <= n:

        if n % x == 0:
            if n // x == x:
                factors.append(x)
            else:
                factors.append(x)
                factors.append(n//x)

        x += 1

    return factors

# Functions: list of factors, seive of primes, gcd of two numbers,
# lcm of two numbers, npr, ncr

def main():
    try:
        for _ in range(inp()):
            n = inp()
            a = input()
            b = input()
            k = 0
            ans = []

            for i in range(n):
                if a[i] != b[i] and i == 0:
                    k += 1
                    ans += [1]
                
                elif a[i] != b[i]:
                    k += 3
                    ans += [i+1, 1, i+1]

            print(k, *ans, sep = " ")

    except Exception as e:
        print(e)

        

# region fastio

BUFSIZE = 8192


class FastIO(IOBase):
    newlines = 0

    def __init__(self, file):
        self._fd = file.fileno()
        self.buffer = BytesIO()
        self.writable = "x" in file.mode or "r" not in file.mode
        self.write = self.buffer.write if self.writable else None

    def read(self):
        while True:
            b = os.read(self._fd, max(os.fstat(self._fd).st_size, BUFSIZE))
            if not b:
                break
            ptr = self.buffer.tell()
            self.buffer.seek(0, 2), self.buffer.write(b), self.buffer.seek(ptr)
        self.newlines = 0
        return self.buffer.read()

    def readline(self):
        while self.newlines == 0:
            b = os.read(self._fd, max(os.fstat(self._fd).st_size, BUFSIZE))
            self.newlines = b.count(b"\n") + (not b)
            ptr = self.buffer.tell()
            self.buffer.seek(0, 2), self.buffer.write(b), self.buffer.seek(ptr)
        self.newlines -= 1
        return self.buffer.readline()

    def flush(self):
        if self.writable:
            os.write(self._fd, self.buffer.getvalue())
            self.buffer.truncate(0), self.buffer.seek(0)


class IOWrapper(IOBase):
    def __init__(self, file):
        self.buffer = FastIO(file)
        self.flush = self.buffer.flush
        self.writable = self.buffer.writable
        self.write = lambda s: self.buffer.write(s.encode("ascii"))
        self.read = lambda: self.buffer.read().decode("ascii")
        self.readline = lambda: self.buffer.readline().decode("ascii")


sys.stdin, sys.stdout = IOWrapper(sys.stdin), IOWrapper(sys.stdout)
input = lambda: sys.stdin.readline().rstrip("\r\n")

# endregion

if __name__ == "__main__":
    main()