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 JAVA):

Solution:
    import java.util.*;
    import java.io.*;

    public class Main {

	static FastScanner scn = new FastScanner();
	static PrintWriter out = new PrintWriter(System.out);
	
	public static void main(String[] HastaLaVistaLa) {
		// Running Number Of TestCases (t)
		int t = scn.nextInt();
		while(t-- > 0)
			solve();
		out.close();
	}

	public static void dummy(){
		int n = scn.nextInt();
		out.println();
	}

	static long MOD = 1000000007L;
	static long[] dp;
	public static void solve() {
		// Main Solution (AC)
		int n = scn.nextInt();
		char[] a = scn.next().toCharArray();
		char[] b = scn.next().toCharArray();
		
		int toLook = n - 1;
		List<Integer> ans = new ArrayList<>();
		for(int i = n - 1; i >= 0; i--) {
			// Handle Case For N == 1
			if(a[i] == b[i]) {
				// If they are already same, then just continue
				// out.println("Middle Fine : " + Arrays.toString(a));
			}else {
				// If Not
				if(a[i] == a[0]) {
					// First is opposite of the current
					ans.add(i+1);

				}else {
					ans.add(1);
					ans.add(i+1);
					if(a[0] == '1') a[0] = '0';
					else a[0] = '1';
				}

				for(int j = 0; j <= i; j++) {
						if(a[j] == '1') a[j] = '0';
						else a[j] = '1';
				}

				// Reverse Part
				int swap = i / 2;
				int p = i;
				// out.println("From " + 0 + " to " + i);
				for(int j = 0; j <= i; j++) {
					if(swap >= 0) {
						char temp = a[j];
						// out.println(j + " " + p);
						a[j] = a[p];
						a[p] = temp;
						p--;
					}else break;
					swap--;
				}
				// out.println("Middle NFin: " + Arrays.toString(a));
			}			
		}
		// out.println("asnwer array -> " + Arrays.toString(a));
		if(ans.size() == 0) out.println(0);
		else {
			out.print(ans.size() + " ");
			for(int i : ans) out.print(i + " ");
			out.println();
		}
	}

	public static long binpow(long n, long m, long mod) {
	        long res = 1;
	        while (m > 0) {
	            if (m % 2 == 1) {
	                res *= n;
	                res %= mod;
	                m--;
	            }
	            n *= n;
	            n %= mod;
	            m /= 2;
	        }
	        return res;
    	}

	public static HashMap<Integer, Integer> CountFrequencies(int[] arr) {
		HashMap<Integer, Integer> map = new HashMap<>();
		for (int i : arr) if (map.containsKey(i)) map.put(i, map.get(i) + 1); else map.put(i, 1);
		return map;
	}

	// Number of Divisor for Range [l, r]
	public static int[] NumberOFDivisors(int l, int r) {
		int[] arr = new int[l - r + 1];
		for(int i = l; i <= r; i++) for(int j = i; j <= r; j += i) arr[j]++;
		return arr;
	}

	public static int LowerBound(int a[], int x) { // x is the target value or key

		  int l = -1,r = a.length;
		  while(l + 1 < r) {
		    int m = (l + r) >>> 1;
		    if(a[m] >= x) r = m;
		    else l = m;

		  }
		  return r;
	}

	static boolean[] prime;
	public static void sieveOfEratosthenes(int n) {

        	prime = new boolean[n+1];
	        for(int i=0;i<n;i++)
	            prime[i] = true;
	        for(int p = 2; p*p <=n; p++) {
	            if(prime[p] == true) {
	                for(int i = p*p; i <= n; i += p)
	                    prime[i] = false;
	            }
	        }
    	}

	public static int UpperBound(long a[], long x) {// x is the key or target value

		    int l = -1,r = a.length;
		    while(l + 1 < r) {
		       int m = (l + r) >>> 1;
		       if(a[m] <= x) l = m;
		       else r = m;
		    }
		    return l + 1;
	}

    	public static long lcm(long a, long b) {
		return (a * b) / gcd(a, b);
	}

	public static long gcd(long a, long b) {
		if (a == 0)
			return b;
		return gcd(b % a, a);
	}

	public static void sort(int[] arr) {
		Random rand = new Random();
		int n = arr.length;
		for(int i = 0; i<n; i++) {
			swap(arr, i, rand.nextInt(n));
		}
		Arrays.sort(arr);
	}

	public static void swap(int[] arr, int i, int j) {
		if(i!=j) {
			arr[i] ^= arr[j];
			arr[j] ^= arr[i];
			arr[i] ^= arr[j];
		}
	}
     
	public static void sortbyColumn(int[][] arr, int col) {
		Arrays.sort(arr, new Comparator<int[]>() {
			public int compare(final int[] entry1, final int[] entry2) {
				if (entry1[col] > entry2[col])
					return 1;
				else
					return -1;
			}
		});
	}

	public static void ArraySort2D(double[][] arr, int xy) {
		// xy == 0, for sorting wrt X-Axis
		// xy == 1, for sorting wrt Y-Axis
		Arrays.sort(arr, Comparator.comparingDouble(o -> o[xy]));
	}
     
	static class FastScanner {
	BufferedReader br=new BufferedReader(new InputStreamReader(System.in));
	StringTokenizer st=new StringTokenizer("");
		String next() {
			while (!st.hasMoreTokens())
				try {
					st=new StringTokenizer(br.readLine());
				} catch (IOException e) {
					e.printStackTrace();
				}
			return st.nextToken();
		}
		
		int nextInt() {
			return Integer.parseInt(next());
		}
		int[] readIntArray(int n) {
			int[] a=new int[n];
			for (int i=0; i<n; i++) a[i]=nextInt();
			return a;
		}
		long[] readLongArray(int n) {
			long[] a=new long[n];
			for (int i=0; i<n; i++) a[i]=nextLong();
			return a;
		}
		long nextLong() {
			return Long.parseLong(next());
		}
	}
}