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.sql.SQLSyntaxErrorException;
import java.util.*;
import java.io.*;
import java.util.stream.StreamSupport;


public class Solution {
    static int mod = 998244353;
    public static void main(String str[]) throws IOException {
//        Reader sc = new Reader();
        BufferedWriter output = new BufferedWriter(new OutputStreamWriter(System.out));
        Scanner sc = new Scanner(System.in);
        int t =sc.nextInt();

        while(t-->0) {
            int n = sc.nextInt();
            int m = sc.nextInt();
            sc.nextLine();
            String[] strs = new String[n];
            String[] st = new String[n-1];
            for(int i=0;i<n;i++)    strs[i] = sc.nextLine();
            for(int i=0;i<n-1;i++)    st[i] = sc.nextLine();
            String ans = "";
            for(int i=0;i<m;i++){
                long tot = 0;
                for(int j=0;j<n-1;j++){
                    tot+=(strs[j].charAt(i)-st[j].charAt(i));
                }
                tot+=strs[n-1].charAt(i);
                char c = (char)tot;
                ans+=c;
            }
            System.out.println(ans);


        }

        output.flush();
    }
//    static long power(long x,long y,long m)
//    {
//        if (y == 0)
//            return 1;
//        long p = power(x, y / 2, m) % m;
//        p = (p * p) % m;
//        long ans = (y % 2 == 0) ? p : (x * p) % m;
//        return ans;
//    }

    // Returns n^(-1) mod p
    static int modInverse(long n, long p)
    {
        return (int)power(n, p - 2, p);
    }

    // Returns nCr % p using Fermat's
    // little theorem.
    static long nCrModPFermat(int n, int r,
                             int p, long[] fac)
    {

        if (n<r)
            return 0;
        // Base case
        if (r == 0)
            return 1;

        // Fill factorial array so that we
        // can find all factorial of r, n
        // and n-r
        long x = modInverse(fac[r], p);
        long y = modInverse(fac[n - r], p);

        return (fac[n] * x
                % p * y
                % p)
                % p;
    }
    static long[] sum(String[] str){
        int n = str[0].length();
        long ans[] = new long[n];
        for(String s: str){
            for(int i=0;i<n;i++)   ans[i]+=s.charAt(i);
        }
        return ans;
    }

    static class tSort implements Comparator<Pair>{

        public int compare(Pair s1, Pair s2) {
            if (s1.b < s2.b)
                return -1;
            else if (s1.b > s2.b)
                return 1;
            return 0;
        }
    }
    static void dfs2(Tree[] arr, int[] ans,boolean[] vis, int curr){
        Collections.sort(arr[curr].al, new Comparator<Integer>() {
            @Override
            public int compare(Integer a, Integer b)
            {
                if(ans[arr[a].a]==-1)  return 1;
                if(ans[arr[b].a]==-1) return -1;
                if(ans[arr[a].a]>=ans[arr[b].a]) return 1;
                else return -1;
            }
        });
        vis[curr] = true;
        for(int j=0;j<arr[curr].al.size();j++){
            int i = arr[curr].al.get(j);
            if(ans[i]==-1 || ans[curr]==-1) ans[i] = -1;
            else    ans[i] = Math.max(ans[i],ans[curr]);
            if(!vis[i]){
                vis[i] = true;
                dfs2(arr,ans,vis,i);
            }
        }
    }
    static void dfs(Tree[] arr, int[] ans, int curr, int n, int parent){
        if(parent!=-1 && ans[parent]==-1)   ans[curr] = -1;
        for(int i: arr[curr].al){
            if(ans[curr]==-1) ans[i]=-1;
            else    if(ans[i]==0){
                ans[i] = 1;
                dfs(arr,ans,i,n,curr);
            }
            else if(ans[i]==1){
                ans[i] = 2;
                boolean visited[] = new boolean[n];
                if(checkCycle(arr,visited,i, i))   ans[i] = -1;
            }
        }
    }
    static boolean checkCycle(Tree[] arr,  boolean[] visited, int curr, int node){
        if(curr==node && visited[curr]) return true;
        if(visited[curr])   return false;
        visited[curr]  = true;
        for(int i: arr[curr].al){
            if(checkCycle(arr, visited, i, node))    return true;
        }
        return false;
    }


    static ArrayList<String> fun( int curr, int n, char c){
        int len = n-curr;
        if(len==0)  return null;
        ArrayList<String> al = new ArrayList<>();
        if(len==1){
            al.add(c+"");
            return al;
        }
        String ss = "";
        for(int i=0;i<len/2;i++){
            ss+=c;
        }
        ArrayList<String> one = fun(len/2+curr, n, (char)(c+1));
        for(String str: one){
            al.add(str+ss);
            al.add(ss+str);
        }
        return al;
    }
    static ArrayList convert(int x, int k){
        ArrayList<Integer> al = new ArrayList<>();
        if(x>0) {
            while (x > 0) {
                al.add(x % k);
                x /= k;
            }
        }
        else    al.add(0);
        return al;
    }




    static int max(int x, int y, int z){
        int ans = Math.max(x,y);
        ans = Math.max(ans, z);
        return ans;
    }
    static int min(int x, int y, int z){
        int ans = Math.min(x,y);
        ans = Math.min(ans, z);
        return ans;
    }

//    static long treeTraversal(Tree arr[], int parent, int x){
//        long tot = 0;
//        for(int i: arr[x].al){
//            if(i!=parent){
//                tot+=treeTraversal(arr, x, i);
//            }
//        }
//        arr[x].child = tot;
//        if(arr[x].child==0) arr[x].child = 1;
//        return tot+1;
//    }

    public static int primeFactors(int n, int k)
    {
        int ans = 0;

        while (n%2==0)
        {
            ans++;
            if(ans>=k)  return k;
            n /= 2;
        }
        for (int i = 3; i <= Math.sqrt(n); i+= 2)
        {
            while (n%i == 0)
            {
                ans++;
                n /= i;
                if(ans>=k)  return k;
            }
        }

        if (n > 2)  ans++;
        return ans;
    }
    static int binaryLow(ArrayList<Integer> arr, int x, int s, int e){
        if(s>=e){
            if(arr.get(s)>=x)  return s;
            else    return s+1;
        }
        int m = (s+e)/2;
        if(arr.get(m)==x)  return m;
        if(arr.get(m)>x)   return binaryLow(arr,x,s,m);
        if(arr.get(m)<x)   return binaryLow(arr,x,m+1,e);
        return 0;
    }
    static int binaryLow(int[] arr, int x, int s, int e){
        if(s>=e){
            if(arr[s]>=x)  return s;
            else    return s+1;
        }
        int m = (s+e)/2;
        if(arr[m]==x)  return m;
        if(arr[m]>x)   return binaryLow(arr,x,s,m);
        if(arr[m]<x)   return binaryLow(arr,x,m+1,e);
        return 0;
    }
    static int binaryHigh(int[] arr, int x, int s, int e){
        if(s>=e){
            if(arr[s]<=x)  return s;
            else    return s-1;
        }
        int m = (s+e)/2;
        if(arr[m]==x)  return m;
        if(arr[m]>x)   return binaryHigh(arr,x,s,m-1);
        if(arr[m]<x)   return binaryHigh(arr,x,m+1,e);
        return 0;
    }


    static void arri(int arr[], int n, Reader sc) throws IOException{
        for(int i=0;i<n;i++){
            arr[i] = sc.nextInt();
        }
    }
    static void arrl(long arr[], int n, Reader sc) throws IOException{
        for(int i=0;i<n;i++){
            arr[i] = sc.nextLong();
        }
    }

    static long gcd(long a, long b)
    {
        if (b == 0)
            return a;
        return gcd(b, a % b);
    }
    static long power(long x, long y, long p)
    {
        long res = 1; // Initialize result

        x = x % p; // Update x if it is more than or
        // equal to p

        if (x == 0)
            return 0; // In case x is divisible by p;

        while (y > 0)
        {

            // If y is odd, multiply x with result
            if ((y & 1) != 0)
                res = (res * x) % p;

            // y must be even now
            y = y >> 1; // y = y/2
            x = (x * x) % p;
        }
        return res%p;
    }

//    static boolean dfs(Tree node, boolean[] visited, int parent, ArrayList<Tree> tt){
//        visited[node.a] = true;
//        boolean b = false;
//        for(int i: node.al){
//            if(tt.get(i).a!=parent){
//                if(visited[tt.get(i).a])    return true;
//                b|= dfs(tt.get(i), visited, node.a, tt);
//            }
//        }
//        return b;
//    }


    static class Pair{
        //        int ind;
        long a=0;
        long b=0;
        //        ArrayList<Integer> ii = new ArrayList<>();
//        Pair( long a, long b){
////            this.ind = i;
//            this.a = a;
//            this.b = b;
//        }

    }
//    static class sortT implements Comparator<Integer> {
//        // Used for sorting in ascending order of
//        // roll number
//        public int compare(Integer a, Integer b)
//        {
//            if(a.ans[a.a]==-1)  return 1;
//            if(b.ans[b.a]==-1) return -1;
//            if(a.ans[a.a]>=a.ans[b.a]) return 1;
//            else return -1;
//        }
//    }
    static class SortbyI implements Comparator<Pair> {
        // Used for sorting in ascending order of
        // roll number
        public int compare(Pair a, Pair b)
        {
            if(a.a>=b.a) return 1;
            else return -1;
        }
    }
    //    static class SortbyD implements Comparator<Pair> {
//        // Used for sorting in ascending order of
//        // roll number
//        public int compare(Pair a, Pair b)
//        {
//            return b.a - a.a;
//        }
//    }
    static int binarySearch(ArrayList<Pair> a, int x, int s, int e){
        if(s>=e){
            if(x<=a.get(s).b)  return s;
            else    return s+1;
        }
        int mid = (e+s)/2;
        if(a.get(mid).b<x){
            return binarySearch(a, x, mid+1, e);
        }
        else    return binarySearch(a,x,s, mid);
    }

    //    static class Edge{
//        int a;
//        int b;
//        int c;
//        int sec;
//        Edge(int a, int b, int c, int sec){
//            this.a = a;
//            this.b = b;
//            this.c = c;
//            this.sec = sec;
//        }
//
//    }
    static class Tree{
        int a;
        int[] ans;
        ArrayList<Integer> al = new ArrayList<>();
        Tree(int a){
            this.a = a;
        }

    }
    static class Reader {
        final private int BUFFER_SIZE = 1 << 16;
        private DataInputStream din;
        private byte[] buffer;
        private int bufferPointer, bytesRead;

        public Reader()
        {
            din = new DataInputStream(System.in);
            buffer = new byte[BUFFER_SIZE];
            bufferPointer = bytesRead = 0;
        }

        public Reader(String file_name) throws IOException
        {
            din = new DataInputStream(
                    new FileInputStream(file_name));
            buffer = new byte[BUFFER_SIZE];
            bufferPointer = bytesRead = 0;
        }

        public String readLine() throws IOException
        {
            byte[] buf = new byte[64]; // line length
            int cnt = 0, c;
            while ((c = read()) != -1) {
                if (c == '\n') {
                    if (cnt != 0) {
                        break;
                    }
                    else {
                        continue;
                    }
                }
                buf[cnt++] = (byte)c;
            }
            return new String(buf, 0, cnt);
        }

        public int nextInt() throws IOException
        {
            int ret = 0;
            byte c = read();
            while (c <= ' ') {
                c = read();
            }
            boolean neg = (c == '-');
            if (neg)
                c = read();
            do {
                ret = ret * 10 + c - '0';
            } while ((c = read()) >= '0' && c <= '9');

            if (neg)
                return -ret;
            return ret;
        }

        public long nextLong() throws IOException
        {
            long ret = 0;
            byte c = read();
            while (c <= ' ')
                c = read();
            boolean neg = (c == '-');
            if (neg)
                c = read();
            do {
                ret = ret * 10 + c - '0';
            } while ((c = read()) >= '0' && c <= '9');
            if (neg)
                return -ret;
            return ret;
        }

        public double nextDouble() throws IOException
        {
            double ret = 0, div = 1;
            byte c = read();
            while (c <= ' ')
                c = read();
            boolean neg = (c == '-');
            if (neg)
                c = read();

            do {
                ret = ret * 10 + c - '0';
            } while ((c = read()) >= '0' && c <= '9');

            if (c == '.') {
                while ((c = read()) >= '0' && c <= '9') {
                    ret += (c - '0') / (div *= 10);
                }
            }

            if (neg)
                return -ret;
            return ret;
        }

        private void fillBuffer() throws IOException
        {
            bytesRead = din.read(buffer, bufferPointer = 0,
                    BUFFER_SIZE);
            if (bytesRead == -1)
                buffer[0] = -1;
        }

        private byte read() throws IOException
        {
            if (bufferPointer == bytesRead)
                fillBuffer();
            return buffer[bufferPointer++];
        }

        public void close() throws IOException
        {
            if (din == null)
                return;
            din.close();
        }
    }


    static boolean isPrime(int n)
    {
        if (n <= 1)
            return false;
        if (n <= 3)
            return true;
        if (n % 2 == 0 ||
                n % 3 == 0)
            return false;

        for (int i = 5;
             i * i <= n; i = i + 6)
            if (n % i == 0 ||
                    n % (i + 2) == 0)
                return false;

        return true;
    }
    static ArrayList<Integer> sieveOfEratosthenes(int n)
    {
        ArrayList<Integer> al = new ArrayList<>();
        // Create a boolean array
        // "prime[0..n]" and
        // initialize all entries
        // it as true. A value in
        // prime[i] will finally be
        // false if i is Not a
        // prime, else true.
        boolean 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] is not changed, then it is a
            // prime
            if (prime[p] == true)
            {
                // Update all multiples of p
                for (int i = p * p; i <= n; i += p)
                    prime[i] = false;
            }
        }

        // Print all prime numbers
        for (int i = 2; i <= n; i++)
        {
            if (prime[i] == true)
                al.add(i);
        }
        return al;
    }

}