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 time,math as mt,bisect,sys
from sys import stdin,stdout
from collections import deque
from fractions import Fraction
from collections import Counter
from collections import OrderedDict
pi=3.14159265358979323846264338327950
def II(): # to take integer input
    return int(stdin.readline())
def IO(): # to take string input
    return stdin.readline()
def IP(): # to take tuple as input
    return map(int,stdin.readline().split())
def L(): # to take list as input
    return list(map(int,stdin.readline().split()))
def P(x): # to print integer,list,string etc..
    return stdout.write(str(x)+"\n")
def PI(x,y): # to print tuple separatedly
    return stdout.write(str(x)+" "+str(y)+"\n")
def lcm(a,b): # to calculate lcm
    return (a*b)//gcd(a,b)
def gcd(a,b): # to calculate gcd
    if a==0:
        return b
    elif b==0:
        return a
    if a>b:
        return gcd(a%b,b)
    else:
        return gcd(a,b%a)
def readTree(): # to read tree
    v=int(input())
    adj=[set() for i in range(v+1)]
    for i in range(v-1):
        u1,u2=In()
        adj[u1].add(u2)
        adj[u2].add(u1)
    return adj,v
def bfs(adj,v): # a schema of bfs
    visited=[False]*(v+1)
    q=deque()
    while q:
        pass
def sieve():
    li=[True]*1000001
    li[0],li[1]=False,False
    for i in range(2,len(li),1):
        if li[i]==True:
            for j in range(i*i,len(li),i):
                li[j]=False
    prime=[]
    for i in range(1000001):
        if li[i]==True:
            prime.append(i)
    return prime
def setBit(n):
    count=0
    while n!=0:
        n=n&(n-1)
        count+=1
    return count
mx=10**7
spf=[mx]*(mx+1)
def SPF():
    spf[1]=1
    for i in range(2,mx+1):
        if spf[i]==mx:
            spf[i]=i
            for j in range(i*i,mx+1,i):
                if i<spf[j]:
                    spf[j]=i
    return
#####################################################################################
mod=10**9+7
def solve(i):
    n=II()
    a,b=input(),input()
    if a==b:
        print(0)
        return
    else:
        fin=[]
        count=0
        for i in range(n):
            if a[i]=='1':
                if i==0:
                    fin.append(1)
                else:
                    fin.append(i)
                    fin.append(i+1)
        for i in range(n-1,-1,-1):
            if b[i]=='1':
                if i==0:
                    fin.append(1)
                else:
                    fin.append(i+1)
                    fin.append(i)
        fin.insert(0,len(fin))
        fin2=[]
        for i in range(n):
            if a[i]=='0':
                if i==0:
                    fin2.append(1)
                else:
                    fin2.append(i)
                    fin2.append(i+1)
        for i in range(n-1,-1,-1):
            if b[i]=='0':
                if i==0:
                    fin2.append(1)
                else:
                    fin2.append(i+1)
                    fin2.append(i)
        fin2.insert(0,len(fin2))
        if fin2[0]<fin[0]:
            print(*fin2)
        else:
            print(*fin)


t=II()
for i in range(t):
    solve(i)

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