Problem: AquaMoon had n strings of length m each. n is an odd number.

When AquaMoon was gone, Cirno tried to pair these n strings together. After making (n-1)/(2) pairs, she found out that there was exactly one string without the pair!

In her rage, she disrupted each pair of strings. For each pair, she selected some positions (at least 1 and at most m) and swapped the letters in the two strings of this pair at the selected positions.

For example, if m = 6 and two strings "abcdef" and "xyzklm" are in one pair and Cirno selected positions 2, 3 and 6 she will swap 'b' with 'y', 'c' with 'z' and 'f' with 'm'. The resulting strings will be "ayzdem" and "xbcklf".

Cirno then stole away the string without pair and shuffled all remaining strings in arbitrary order.

AquaMoon found the remaining n-1 strings in complete disarray. Also, she remembers the initial n strings. She wants to know which string was stolen, but she is not good at programming. Can you help her?

Input

This problem is made as interactive. It means, that your solution will read the input, given by the interactor. But the interactor will give you the full input at the beginning and after that, you should print the answer. So you should solve the problem, like as you solve the usual, non-interactive problem because you won't have any interaction process. The only thing you should not forget is to flush the output buffer, after printing the answer. Otherwise, you can get an "Idleness limit exceeded" verdict. Refer to the [interactive problems guide](https://codeforces.com/blog/entry/45307) for the detailed information about flushing the output buffer.

The input consists of multiple test cases. The first line contains a single integer t (1 ≤ t ≤ 100) — the number of test cases.

The first line of each test case contains two integers n, m (1 ≤ n ≤ 10^5, 1 ≤ m ≤ 10^5) — the number of strings and the length of each string, respectively.

The next n lines each contain a string with length m, describing the original n strings. All string consists of lowercase Latin letters.

The next n-1 lines each contain a string with length m, describing the strings after Cirno exchanged and reordered them.

It is guaranteed that n is odd and that the sum of n ⋅ m over all test cases does not exceed 10^5.

Hack format:

The first line should contain a single integer t. After that t test cases should follow in the following format:

The first line should contain two integers n and m.

The following n lines should contain n strings of length m, describing the original strings.

The following (n-1)/(2) lines should describe the pairs. They should contain, in the following order: the index of the first string i (1 ≤ i ≤ n), the index of the second string j (1 ≤ j ≤ n, i ≠ j), the number of exchanged positions k (1 ≤ k ≤ m), and the list of k positions that are exchanged (k distinct indices from 1 to m in any order).

The final line should contain a permutation of integers from 1 to n, describing the way the strings should be reordered. The strings will be placed in the order indices placed in this permutation, the stolen string index will be ignored.

Output

For each test case print a single line with the stolen string.

Example

Input


3
3 5
aaaaa
bbbbb
ccccc
aaaaa
bbbbb
3 4
aaaa
bbbb
cccc
aabb
bbaa
5 6
abcdef
uuuuuu
kekeke
ekekek
xyzklm
xbcklf
eueueu
ayzdem
ukukuk


Output


ccccc
cccc
kekeke

Note

In the first test case, "aaaaa" and "bbbbb" exchanged all positions, and "ccccc" is the stolen string.

In the second test case, "aaaa" and "bbbb" exchanged two first positions, and "cccc" is the stolen string.

This is the first test in the hack format: 
    
    
      
    3  
    3 5  
    aaaaa  
    bbbbb  
    ccccc  
    1 2 5 1 2 3 4 5  
    2 1 3  
    3 4  
    aaaa  
    bbbb  
    cccc  
    1 2 2 1 2  
    2 1 3  
    5 6  
    abcdef  
    uuuuuu  
    kekeke  
    ekekek  
    xyzklm  
    1 5 3 2 3 6  
    2 4 3 2 4 6  
    5 4 1 2 3  
    

Solution (in JAVA):

Solution:
import java.io.*;
import java.nio.charset.StandardCharsets;
import java.util.*;
    
public class Solution {

    private static class Item {
        String s;
        int sc;

        static Item of(String s) {
            Item it = new Item();
            it.s = s;
            int x = 0;
            for (char ch : s.toCharArray()){
                x += (int)ch;
            }
            it.sc = x;
            return it;
        }

        int getSc() {
            return sc;
        }

        public String toString() {
            return String.format("%s -> %d\n", s, sc);
        }
    }

    public static void main(String[] args) throws IOException {
        BufferedReader br = new BufferedReader(I.stdInputStream());
        int t = I.inputInt(br);
        StringBuilder sb = new StringBuilder();
        while (t-- > 0) {
            int[] spec = I.inputIntArray(br);
            int n = spec[0], m = spec[1];
            int[] or = new int[m];
            int[] og = new int[m];
            for (int i = 0; i < n; i++) {
                String s = I.inputString(br);
                char[] chs = s.toCharArray();
                for (int j = 0; j < s.length(); j++) {
                    or[j] += (int)chs[j];
                }
            }
            for (int i = 0; i < n - 1; i++) {
                String s = I.inputString(br);
                char[] chs = s.toCharArray();
                for (int j = 0; j < s.length(); j++) {
                    og[j] += (int)chs[j];
                }
            }
            char[] x = new char[m];
            for (int i = 0; i < m; i++) {
                x[i] = (char)(or[i] - og[i]);
            }
            sb.append(new String(x)).append("\n");
        }
        O.print(sb);
    }

    public static class S {

        public static <T> String string(T val) {
            return val + "\n";
        }

        public static String string(int[] array) {
            StringBuilder sb = new StringBuilder();
            openingBracket(sb);
            for (int in : array) sb.append(in).append(", ");
            if (array.length != 0) deleteLastComma(sb);
            closingBracket(sb);
            return sb.toString();
        }

        public static String string(long[] array) {
            StringBuilder sb = new StringBuilder();
            openingBracket(sb);
            for (long in : array) sb.append(in).append(", ");
            if (array.length != 0) deleteLastComma(sb);
            closingBracket(sb);
            return sb.toString();
        }

        public static String string(double[] array) {
            StringBuilder sb = new StringBuilder();
            openingBracket(sb);
            for (double in : array) sb.append(in).append(", ");
            if (array.length != 0) deleteLastComma(sb);
            closingBracket(sb);
            return sb.toString();
        }

        public static String string(boolean[] array) {
            StringBuilder sb = new StringBuilder();
            openingBracket(sb);
            for (boolean in : array) sb.append(in ? "T" : "F").append(", ");
            if (array.length != 0) deleteLastComma(sb);
            closingBracket(sb);
            return sb.toString();
        }

        public static String string(char[] array) {
            StringBuilder sb = new StringBuilder();
            openingBracket(sb);
            for (char in : array) sb.append(in).append(", ");
            if (array.length != 0) deleteLastComma(sb);
            closingBracket(sb);
            return sb.toString();
        }

        public static String string(String[] array) {
            StringBuilder sb = new StringBuilder();
            openingBracket(sb);
            for (String in : array) sb.append(in).append(", ");
            if (array.length != 0) deleteLastComma(sb);
            closingBracket(sb);
            return sb.toString();
        }

        public static String string(int[][] array) {
            StringBuilder sb = new StringBuilder();
            openingBracketWithNewLine(sb);
            for (int[] in : array) sb.append("  ").append(string(in));
            closingBracket(sb);
            return sb.toString();
        }

        public static String string(long[][] array) {
            StringBuilder sb = new StringBuilder();
            openingBracketWithNewLine(sb);
            for (long[] in : array) sb.append("  ").append(string(in));
            closingBracket(sb);
            return sb.toString();
        }

        public static String string(double[][] array) {
            StringBuilder sb = new StringBuilder();
            openingBracketWithNewLine(sb);
            for (double[] in : array) sb.append("  ").append(string(in));
            closingBracket(sb);
            return sb.toString();
        }

        public static <T> String string(boolean[][] array) {
            StringBuilder sb = new StringBuilder();
            openingBracketWithNewLine(sb);
            for (boolean[] in : array) sb.append("  ").append(string(in));
            closingBracket(sb);
            return sb.toString();
        }

        public static String string(char[][] array) {
            StringBuilder sb = new StringBuilder();
            openingBracketWithNewLine(sb);
            for (char[] in : array) sb.append("  ").append(string(in));
            closingBracket(sb);
            return sb.toString();
        }

        public static String string(String[][] array) {
            StringBuilder sb = new StringBuilder();
            openingBracketWithNewLine(sb);
            for (String[] in : array) sb.append("  ").append(string(in));
            closingBracket(sb);
            return sb.toString();
        }

        public static <T> String stringi(List<T> list) {
            StringBuilder sb = new StringBuilder();
            for (int i = 0; i < list.size(); i++) sb.append(i).append(": ").append(list.get(i)).append("\n");
            return sb.toString();
        }

        public static <T> String string(Collection<T> collection) {
            StringBuilder sb = new StringBuilder();
            openingBracket(sb);
            for (T t : collection) sb.append(t).append(", ");
            if (!collection.isEmpty()) deleteLastComma(sb);
            closingBracket(sb);
            return sb.toString();
        }

        public static <T> String string2D(Collection<Collection<T>> collection) {
            StringBuilder sb = new StringBuilder();
            openingBracketWithNewLine(sb);
            for (Collection<T> t : collection) sb.append("  ").append(string(t));
            closingBracket(sb);
            return sb.toString();
        }

        public static <T> String string2Di(List<Collection<T>> list) {
            StringBuilder sb = new StringBuilder();
            openingBracketWithNewLine(sb);
            for (int i = 0; i < list.size(); i++) sb.append("  ").append(i).append(": ").append(string(list.get(i)));
            closingBracket(sb);
            return sb.toString();
        }

        public static <E, V> String string(Map<E, V> map) {
            StringBuilder sb = new StringBuilder();
            for (Map.Entry<E, V> entry : map.entrySet())
                sb.append(entry.getKey()).append(": ").append(entry.getValue()).append("\n");
            sb.append("\n");
            return sb.toString();
        }

        private static void openingBracket(StringBuilder sb) {
            sb.append("[");
        }

        private static void openingBracketWithNewLine(StringBuilder sb) {
            sb.append("[\n");
        }

        private static void closingBracket(StringBuilder sb) {
            sb.append("]\n");
        }

        private static void deleteLastComma(StringBuilder sb) {
            sb.delete(sb.length() - 2, sb.length());
        }
    }

    public static class I {

        public static int inputInt(BufferedReader br) throws IOException {
            return Integer.parseInt(br.readLine());
        }

        public static int[] inputIntArray(BufferedReader br) throws IOException {
            String[] spec = br.readLine().split(" ");
            int[] arr = new int[spec.length];
            for (int i = 0; i < spec.length; i++) arr[i] = Integer.parseInt(spec[i]);
            return arr;
        }

        public static long inputLong(BufferedReader br) throws IOException {
            return Long.parseLong(br.readLine());
        }

        public static long[] inputLongArray(BufferedReader br) throws IOException {
            String[] spec = br.readLine().split(" ");
            long[] arr = new long[spec.length];
            for (int i = 0; i < spec.length; i++) arr[i] = Long.parseLong(spec[i]);
            return arr;
        }

        public static String inputString(BufferedReader br) throws IOException {
            return br.readLine();
        }

        public static String[] inputStringArray(BufferedReader br) throws IOException {
            return br.readLine().split(" ");
        }

        private static InputStreamReader inputStream() throws IOException {
            return ("why in the world not?".equals(System.getenv("LOCAL_CODING")))
                    ? fileInputStream() : stdInputStream();
        }

        private static InputStreamReader stdInputStream() {
            return new InputStreamReader(System.in);
        }

        private static InputStreamReader fileInputStream() throws FileNotFoundException {
            return new InputStreamReader(new FileInputStream("input.txt"), StandardCharsets.UTF_8);
        }
    }

    public static class O {

        public static void attach() {
            debug("", false);
        }

        public static void debugNewLine() {
            debug("\n");
        }

        public static void debug(int val) {
            debug(String.valueOf(val));
        }

        public static void debug(long val) {
            debug(String.valueOf(val));
        }

        public static void debug(boolean val) {
            debug(val ? "T" : "F");
        }

        public static void debug(String text) {
            debug(text, true);
        }

        public static void debug(String text, boolean append) {
            if (!"why in the world not?".equals(System.getenv("LOCAL_CODING"))) return;
            try {
                FileWriter fileWriter = new FileWriter("debug.txt", append);
                fileWriter.write(text);
                fileWriter.close();
            } catch (IOException e) {
                e.printStackTrace();
            }
        }

        public static <T> void print(T object) {
            System.out.println(object);
        }
    }
}