This problem is different from the hard version. In this version Ujan makes exactly one exchange. You can hack this problem only if you solve both problems.

After struggling and failing many times, Ujan decided to try to clean up his house again. He decided to get his strings in order first.

Ujan has two distinct strings s and t of length n consisting of only of lowercase English characters. He wants to make them equal. Since Ujan is lazy, he will perform the following operation exactly once: he takes two positions i and j (1 ≤ i,j ≤ n, the values i and j can be equal or different), and swaps the characters s_i and t_j. Can he succeed?

Note that he has to perform this operation exactly once. He has to perform this operation.

Input

The first line contains a single integer k (1 ≤ k ≤ 10), the number of test cases.

For each of the test cases, the first line contains a single integer n (2 ≤ n ≤ 10^4), the length of the strings s and t. 

Each of the next two lines contains the strings s and t, each having length exactly n. The strings consist only of lowercase English letters. It is guaranteed that strings are different.

Output

For each test case, output "Yes" if Ujan can make the two strings equal and "No" otherwise.

You can print each letter in any case (upper or lower).

Example

Input


4
5
souse
houhe
3
cat
dog
2
aa
az
3
abc
bca


Output


Yes
No
No
No

Note

In the first test case, Ujan can swap characters s_1 and t_4, obtaining the word "house".

In the second test case, it is not possible to make the strings equal using exactly one swap of s_i and t_j.
import java.io.*;
import java.math.BigInteger;
import java.util.*;



public class Main {

    private static Set<List<Integer>> permutations;
    private static final double LOAD_FACTOR = 0.75;

    public static void main(String[] args) throws IOException {
        InputStream inputStream = System.in;
        OutputStream outputStream = System.out;
        InputReader in = new InputReader(inputStream);
        InputReader.OutputWriter out = new InputReader.OutputWriter(outputStream);
        Scanner scanner = new Scanner(System.in);

        /*int q = in.nextInt();
        while (q-->0) {
            int n = in.nextInt();
            int [] a = new int[n];
            Map<Integer,Integer> map = new TreeMap<>();
            for (int i = 0; i < a.length; i++) {
                a[i] = in.nextInt();
                map.put(a[i],map.getOrDefault(a[i], 0 ) + 1);
            }
            int max = 0;
            for (Map.Entry<Integer,Integer> m : map.entrySet()) {
                max = Math.max(max,m.getValue());
            }

        }*/

        int q = in.nextInt();
        while (q-->0) {
            int n = in.nextInt();
            String s = in.next();
            String t = in.next();
            if(can(s,t)) out.println("Yes");
            else out.println("No");
        }
        out.flush();
    }

    private static boolean can(String s, String t) {
        int num = 0;
        char a = ' ';
        char b = ' ';
        char c = ' ';
        char d = ' ';
        for (int i = 0; i < s.length(); i++) {
            if(s.charAt(i)!=t.charAt(i)) {
                if(a == ' ') {
                    a = s.charAt(i);
                    b = t.charAt(i);
                }
                else {
                    c = s.charAt(i);
                    d = t.charAt(i);
                }
                num++;
            }
            if(num > 2) return false;
        }

        return num == 0 ||  a == c && b == d;
    }
    private static boolean [] erath() {
        boolean[] isPrime = new boolean[200_000 + 1];
        Arrays.fill(isPrime,true);
        isPrime[0] = false;
        isPrime[1] = false;
        int n = isPrime.length - 1;
        for (int i = 2; i*i<=n; i++) {
            if(isPrime[i]) {
                for (int j = i*i; j <=n; j+=i) {
                    isPrime[j] = false;
                }
            }
        }
        return isPrime;
    }



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


    private static int factorization(long n) {
        Set<Long> set = new HashSet<>();
        for(long i = 2; i * i <=n; i++) {
            while (n % i == 0) {
                set.add(i);
                n /= i;
            }
        }
        if(n > 1) set.add(n);
        return set.size();
    }

    private static void permute(int [] a, int l, int r) {
        if(l == r) {
            List<Integer> list = new ArrayList<>();
            for(int i : a) list.add(i);
            permutations.add(list);
        }
        else {
            for (int i = l; i <=r; i++) {
                swap(a,l,i);
                permute(a,l+1,r);
                swap(a,l,i);
            }
        }
    }
    private static void swap(int [] a, int l, int r) {
        int temp = a[l];
        a[l] = a[r];
        a[r] = temp;
    }

}

class InputReader extends BufferedReader {
    StringTokenizer tokenizer;

    public InputReader(InputStream inputStream) {
        super(new InputStreamReader(inputStream), 32768);
    }

    public InputReader(String filename) {
        super(new InputStreamReader(Thread.currentThread().getContextClassLoader().getResourceAsStream(filename)));
    }

    public String next() {
        while (tokenizer == null || !tokenizer.hasMoreTokens()) {
            try {
                tokenizer = new StringTokenizer(readLine());
            } catch (IOException e) {
                throw new RuntimeException();
            }
        }
        return tokenizer.nextToken();
    }

    public Integer nextInt(){
        return Integer.valueOf(next());
    }
    public Long nextLong() {
        return  Long.valueOf(next());
    }
    public Double nextDouble() {
        return Double.valueOf(next());
    }
    static class OutputWriter extends PrintWriter {
        public OutputWriter(OutputStream outputStream) {
            super(outputStream);
        }

        public OutputWriter(Writer writer) {
            super(writer);
        }

        public OutputWriter(String filename) throws FileNotFoundException {
            super(filename);
        }

        public void close() {
            super.close();
        }
    }
}