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.
def split(word): 
    return [char for char in word]
def flip(li,e):
    for i in range(e):
        if(li[i]=='1'):
            li[i]='0'
        else:
            li[i]='1'
    return li
def rev(li,e):
    liref=li[0:e]
    liref=liref[::-1]
    for i in range(len(liref)):
        li[i]=liref[i]
    return li

t=int(input())
for _ in range(t):
    n1=int(input())
    s1=input()
    s2=input()
    li2=split(s2)
    li1=split(s1)
    i=n1-1
    anslist=[]
   
    while(i>=0):
        if(i==0):
            if(li1[0]!=li2[0]):
                anslist.append(1)
            break
                
       
        if(li1[i]!=li2[i]):
            j=i
            if(li1[0]!=li2[i]):
                anslist.append(i+1)
                li1=flip(li1,i+1)
                li1=rev(li1,i+1)
                
                
                
            else:
                j=i
                for k in range(i-1,-1,-1):
                    if(li1[k]==li2[i]):
                        j=k
                        break
                li1=flip(li1,j+1)
                li1=rev(li1,j+1)
                
               
                anslist.append(j+1)
                anslist.append(i+1)
                li1=flip(li1,i+1)
                li1=rev(li1,i+1)
        
        i=i-1
   
   
    print(len(anslist),end=" ")
    for i in anslist:
        print(i,end=" ")
    print()
                        
                        
        
        
    
    
        
        