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.util.*;
import java.lang.*;

public class codeforces {
    public static void main(String[] args) {
        InputStream inputStream = System.in;
        OutputStream outputStream = System.out;
        if (System.getProperty("ONLINE_JUDGE") == null) {
            long startTime = System.currentTimeMillis();
            try {
                sc = new InputReader(new FileInputStream("input.txt"));
                out = new PrintWriter(new FileOutputStream("output.txt"));
                pr = new PrintWriter(new FileOutputStream("error.txt"));
            } catch (Exception ignored) {
            }
            int t = 1;
            int tt = t;
            t = sc.nextInt();
            while (t-- > 0) {
                solve();
            }
            long endTime = System.currentTimeMillis();
            System.out.println("Time: " + (endTime - startTime) / tt + " ms");
            out.flush();
            pr.flush();

        } else {
            sc = new InputReader(inputStream);
            out = new PrintWriter(outputStream);
            pr = new PrintWriter(outputStream);
            int t = 1;
            t = sc.nextInt();
            while (t-- > 0) {
                solve();
            }
            out.flush();
        }
    }

    public static void solve() {
        n = sc.nextInt();
        m = sc.nextInt();
        int[][] dp = new int[m][26];
        fill(dp, 0);
        for (int i = 0; i < n; i++) {
            s = sc.next();
            for (int j = 0; j < m; j++) {
                dp[j][s.charAt(j) - 'a']++;
            }
        }
        for (int i = n + 1; i < n * 2; i++) {
            s = sc.next();
            for (int j = 0; j < m; j++) {
                dp[j][s.charAt(j) - 'a']--;
            }
        }
        for (int i = 0; i < m; ++i)
            for (int j = 0; j < 26; ++j)
                if (dp[i][j] > 0) {
                    out.print((char) (j + 'a'));
                    out.flush();
                }
        out.println("");
        out.flush();
    }

    /*******************************************************************/
    /*
     * Set Iterator Iterator value = set.iterator(); Displaying the values after
     * iterating through the iterator
     * System.out.println("The iterator values are: "); while (value.hasNext()) {
     * System.out.println(value.next()); }
     */

    /*
     * Map Iterator: for (Map.Entry<Integer, Integer> entry : map.entrySet()){
     * System.out.println("Key => " + entry.getKey() + ", Value => " +
     * entry.getValue());}
     */

    // Globals

    public static int n, m;
    public static final int inf = Integer.MAX_VALUE;
    public static final int minf = Integer.MIN_VALUE;
    public static final int mod = 1000000007;
    public static final int ml = (int) 1e9;
    public static final int template_array_size = (int) 2e6 + 16813;
    // public static long[] arr = new long[template_array_size];
    // public static long[] arr2 = new long[template_array_size];
    // public static long[] dp = new long[template_array_size];
    public static String s = "";
    public static InputReader sc;
    public static PrintWriter out;
    public static PrintWriter pr;

    // Pair

    static class Pair {
        int first, second;

        Pair(int x, int y) {
            this.first = x;
            this.second = y;
        }
    }

    // FastReader Class

    static class InputReader {
        public BufferedReader reader;
        public StringTokenizer tokenizer;

        public InputReader(InputStream stream) {
            reader = new BufferedReader(new InputStreamReader(stream), 32768);
            tokenizer = null;
        }

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

        public int nextInt() {
            return Integer.parseInt(next());
        }

        public long nextLong() {
            return Long.parseLong(next());
        }

        public double nextDouble() {
            return Double.parseDouble(next());
        }
    }

    // Req Functions
    public static void fill(int[][] dp, int x) {
        for (int i = 0; i < dp.length; ++i) {
            for (int j = 0; j < dp[0].length; ++j) {
                dp[i][j] = x;
            }
        }
    }

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

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

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

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

    public static long nCr(int n, int k) {
        long ans = 1L;
        k = k > n - k ? n - k : k;
        int j = 1;
        for (; j <= k; j++, n--) {
            if (n % j == 0) {
                ans *= n / j;
            } else if (ans % j == 0) {
                ans = ans / j * n;
            } else {
                ans = (ans * n) / j;
            }
        }
        return ans;
    }

    public static String reverseString(String input) {
        StringBuilder str = new StringBuilder("");

        for (int i = input.length() - 1; i >= 0; i--) {
            str.append(input.charAt(i));
        }
        return str.toString();
    }

    public static int maxOf3(int x, int y, int z) {
        return Math.max(x, Math.max(y, z));
    }

    public static int minof3(int x, int y, int z) {
        return Math.min(x, Math.min(y, z));
    }

    public static long maxOf3(long x, long y, long z) {
        return Math.max(x, Math.max(y, z));
    }

    public static long minof3(long x, long y, long z) {
        return Math.min(x, Math.min(y, z));
    }

    public static void arrInput(int[] arr, int n) {
        for (int i = 0; i < n; i++)
            arr[i] = sc.nextInt();
    }

    public static void arrInput(long[] arr, int n) {
        for (int i = 0; i < n; i++)
            arr[i] = sc.nextLong();
    }

    public static void arrInput(Pair[] pair, int n) {
        for (int i = 0; i < n; i++)
            pair[i] = new Pair(sc.nextInt(), sc.nextInt());
    }

    public static int maxarrInput(int[] arr, int n) {
        int max = minf;
        for (int i = 0; i < n; i++) {
            arr[i] = sc.nextInt();
            max = Math.max(max, arr[i]);
        }
        return max;

    }

    public static long maxarrInput(long[] arr, int n) {
        long max = minf;
        for (int i = 0; i < n; i++) {
            arr[i] = sc.nextLong();
            max = Math.max(max, arr[i]);
        }
        return max;
    }

    public static int minarrInput(int[] arr, int n) {
        int min = inf;
        for (int i = 0; i < n; i++) {
            arr[i] = sc.nextInt();
            min = Math.max(min, arr[i]);
        }
        return min;
    }

    public static long minarrInput(long[] arr, int n) {
        long min = inf;
        for (int i = 0; i < n; i++) {
            arr[i] = sc.nextLong();
            min = Math.max(min, arr[i]);
        }
        return min;
    }

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

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

    public static void merge(int arr[], int l, int m, int r) {
        int n1 = m - l + 1;
        int n2 = r - m;
        int L[] = new int[n1];
        int R[] = new int[n2];
        for (int i = 0; i < n1; ++i)
            L[i] = arr[l + i];
        for (int j = 0; j < n2; ++j)
            R[j] = arr[m + 1 + j];
        int i = 0, j = 0;
        int k = l;
        while (i < n1 && j < n2) {
            if (L[i] >= R[j]) {
                arr[k] = L[i];
                i++;
            } else {
                arr[k] = R[j];
                j++;
            }
            k++;
        }
        while (i < n1) {
            arr[k] = L[i];
            i++;
            k++;
        }
        while (j < n2) {
            arr[k] = R[j];
            j++;
            k++;
        }
    }

    public static void reversesort(int arr[], int l, int r) {
        if (l < r) {
            int m = l + (r - l) / 2;
            reversesort(arr, l, m);
            reversesort(arr, m + 1, r);
            merge(arr, l, m, r);
        }
    }

    public static void merge(long arr[], int l, int m, int r) {
        int n1 = m - l + 1;
        int n2 = r - m;
        long L[] = new long[n1];
        long R[] = new long[n2];
        for (int i = 0; i < n1; ++i)
            L[i] = arr[l + i];
        for (int j = 0; j < n2; ++j)
            R[j] = arr[m + 1 + j];
        int i = 0, j = 0;
        int k = l;
        while (i < n1 && j < n2) {
            if (L[i] >= R[j]) {
                arr[k] = L[i];
                i++;
            } else {
                arr[k] = R[j];
                j++;
            }
            k++;
        }
        while (i < n1) {
            arr[k] = L[i];
            i++;
            k++;
        }
        while (j < n2) {
            arr[k] = R[j];
            j++;
            k++;
        }
    }

    public static void reversesort(long arr[], int l, int r) {
        if (l < r) {
            int m = l + (r - l) / 2;
            reversesort(arr, l, m);
            reversesort(arr, m + 1, r);
            merge(arr, l, m, r);
        }
    }

    // debug

    public static boolean sysFlag = System.getProperty("ONLINE_JUDGE") == null;

    public static void debug(int[][] dp) {
        if (sysFlag) {
            for (int i = 0; i < dp.length; ++i) {
                pr.print(i + "--> ");
                for (int j = 0; j < dp[0].length; ++j) {
                    pr.print(dp[i][j] + " ");
                }
                pr.println("");
            }
        }
    }

    public static void debug(long[][] dp) {
        if (sysFlag) {
            for (int i = 0; i < dp.length; ++i) {
                pr.print(i + "--> ");
                for (int j = 0; j < dp[0].length; ++j) {
                    pr.print(dp[i][j] + " ");
                }
                pr.println("");
            }
        }
    }

    public static void debug(int x) {
        if (sysFlag)
            pr.println("Int-Ele: " + x);
    }

    public static void debug(String x) {
        if (sysFlag)
            pr.println("String: " + x);
    }

    public static void debug(char x) {
        if (sysFlag)
            pr.println("Char: " + x);
    }

    public static void debug(long x) {
        if (sysFlag)
            pr.println("Long-Ele: " + x);
    }

    public static void debug(int[] arr, int n) {
        if (sysFlag) {
            for (int i = 0; i < n; ++i) {
                pr.println(i + " -> " + arr[i]);
            }
        }
    }

    public static void debug(char[] arr) {
        if (sysFlag) {
            for (int i = 0; i < arr.length; ++i) {
                pr.println(i + " -> " + arr[i]);
            }
        }
    }

    public static void debug(long[] arr, int n) {
        if (sysFlag) {
            for (int i = 0; i < n; ++i) {
                pr.println(i + " -> " + arr[i]);
            }
        }
    }

    public static void debug(ArrayList<Integer> list) {
        if (sysFlag) {
            for (int i = 0; i < list.size(); ++i) {
                pr.println(i + " -> " + list.get(i));
            }
        }
    }

    public static void Ldebug(ArrayList<Long> list) {
        if (sysFlag) {
            for (int i = 0; i < list.size(); ++i) {
                pr.println(i + " -> " + list.get(i));
            }
        }
    }

    public static void debugmapII(HashMap<Integer, Integer> map) {
        if (sysFlag) {
            for (Map.Entry<Integer, Integer> entry : map.entrySet())
                pr.println("Key => " + entry.getKey() + ", Value => " + entry.getValue());
        }
    }

    public static void debugmapLI(HashMap<Long, Integer> map) {
        if (sysFlag) {
            for (Map.Entry<Long, Integer> entry : map.entrySet())
                pr.println("Key => " + entry.getKey() + ", Value => " + entry.getValue());
        }
    }

    public static void debugmapLL(HashMap<Long, Long> map) {
        if (sysFlag) {
            for (Map.Entry<Long, Long> entry : map.entrySet())
                pr.println("Key => " + entry.getKey() + ", Value => " + entry.getValue());
        }
    }

    public static void debugmapIL(HashMap<Integer, Long> map) {
        if (sysFlag) {
            for (Map.Entry<Integer, Long> entry : map.entrySet())
                pr.println("Key => " + entry.getKey() + ", Value => " + entry.getValue());
        }
    }

    public static void debugmapSL(HashMap<String, Long> map) {
        if (sysFlag) {
            for (Map.Entry<String, Long> entry : map.entrySet())
                pr.println("Key => " + entry.getKey() + ", Value => " + entry.getValue());
        }
    }

    public static void debugmapCL(HashMap<Character, Long> map) {
        if (sysFlag) {
            for (Map.Entry<Character, Long> entry : map.entrySet())
                pr.println("Key => " + entry.getKey() + ", Value => " + entry.getValue());
        }
    }

    public static void debugmapSI(HashMap<String, Integer> map) {
        if (sysFlag) {
            for (Map.Entry<String, Integer> entry : map.entrySet())
                pr.println("Key => " + entry.getKey() + ", Value => " + entry.getValue());
        }
    }

    public static void debugmapCI(HashMap<Character, Integer> map) {
        if (sysFlag) {
            for (Map.Entry<Character, Integer> entry : map.entrySet())
                pr.println("Key => " + entry.getKey() + ", Value => " + entry.getValue());
        }
    }

    public static void debug(Set<Integer> set) {
        if (sysFlag) {
            Iterator value = set.iterator();
            int i = 1;
            while (value.hasNext()) {
                pr.println((i++) + "-> " + value.next());
            }
        }
    }
}