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 PYTHON3):

Solution:
# ---------------------------iye ha aam zindegi---------------------------------------------
import math
import random
import heapq,bisect
import sys
from collections import deque, defaultdict
from fractions import Fraction
import sys
import threading
from collections import defaultdict
threading.stack_size(10**8)
mod = 10 ** 9 + 7
mod1 = 998244353

# ------------------------------warmup----------------------------
import os
import sys
from io import BytesIO, IOBase
sys.setrecursionlimit(300000)

BUFSIZE = 8192


class FastIO(IOBase):
    newlines = 0

    def __init__(self, file):
        self._fd = file.fileno()
        self.buffer = BytesIO()
        self.writable = "x" in file.mode or "r" not in file.mode
        self.write = self.buffer.write if self.writable else None

    def read(self):
        while True:
            b = os.read(self._fd, max(os.fstat(self._fd).st_size, BUFSIZE))
            if not b:
                break
            ptr = self.buffer.tell()
            self.buffer.seek(0, 2), self.buffer.write(b), self.buffer.seek(ptr)
        self.newlines = 0
        return self.buffer.read()

    def readline(self):
        while self.newlines == 0:
            b = os.read(self._fd, max(os.fstat(self._fd).st_size, BUFSIZE))
            self.newlines = b.count(b"\n") + (not b)
            ptr = self.buffer.tell()
            self.buffer.seek(0, 2), self.buffer.write(b), self.buffer.seek(ptr)
        self.newlines -= 1
        return self.buffer.readline()

    def flush(self):
        if self.writable:
            os.write(self._fd, self.buffer.getvalue())
            self.buffer.truncate(0), self.buffer.seek(0)


class IOWrapper(IOBase):
    def __init__(self, file):
        self.buffer = FastIO(file)
        self.flush = self.buffer.flush
        self.writable = self.buffer.writable
        self.write = lambda s: self.buffer.write(s.encode("ascii"))
        self.read = lambda: self.buffer.read().decode("ascii")
        self.readline = lambda: self.buffer.readline().decode("ascii")


sys.stdin, sys.stdout = IOWrapper(sys.stdin), IOWrapper(sys.stdout)
input = lambda: sys.stdin.readline().rstrip("\r\n")


# -------------------game starts now----------------------------------------------------import math
class TreeNode:
    def __init__(self, k, v):
        self.key = k
        self.value = v
        self.left = None
        self.right = None
        self.parent = None
        self.height = 1
        self.num_left = 1
        self.num_total = 1


class AvlTree:

    def __init__(self):
        self._tree = None

    def add(self, k, v):
        if not self._tree:
            self._tree = TreeNode(k, v)
            return
        node = self._add(k, v)
        if node:
            self._rebalance(node)

    def _add(self, k, v):
        node = self._tree
        while node:
            if k < node.key:
                if node.left:
                    node = node.left
                else:
                    node.left = TreeNode(k, v)
                    node.left.parent = node
                    return node.left
            elif node.key < k:
                if node.right:
                    node = node.right
                else:
                    node.right = TreeNode(k, v)
                    node.right.parent = node
                    return node.right
            else:
                node.value = v
                return

    @staticmethod
    def get_height(x):
        return x.height if x else 0

    @staticmethod
    def get_num_total(x):
        return x.num_total if x else 0

    def _rebalance(self, node):

        n = node
        while n:
            lh = self.get_height(n.left)
            rh = self.get_height(n.right)
            n.height = max(lh, rh) + 1
            balance_factor = lh - rh
            n.num_total = 1 + self.get_num_total(n.left) + self.get_num_total(n.right)
            n.num_left = 1 + self.get_num_total(n.left)

            if balance_factor > 1:
                if self.get_height(n.left.left) < self.get_height(n.left.right):
                    self._rotate_left(n.left)
                self._rotate_right(n)
            elif balance_factor < -1:
                if self.get_height(n.right.right) < self.get_height(n.right.left):
                    self._rotate_right(n.right)
                self._rotate_left(n)
            else:
                n = n.parent

    def _remove_one(self, node):
        """
        Side effect!!! Changes node. Node should have exactly one child
        """
        replacement = node.left or node.right
        if node.parent:
            if AvlTree._is_left(node):
                node.parent.left = replacement
            else:
                node.parent.right = replacement
            replacement.parent = node.parent
            node.parent = None
        else:
            self._tree = replacement
            replacement.parent = None
        node.left = None
        node.right = None
        node.parent = None
        self._rebalance(replacement)

    def _remove_leaf(self, node):
        if node.parent:
            if AvlTree._is_left(node):
                node.parent.left = None
            else:
                node.parent.right = None
            self._rebalance(node.parent)
        else:
            self._tree = None
        node.parent = None
        node.left = None
        node.right = None

    def remove(self, k):
        node = self._get_node(k)
        if not node:
            return
        if AvlTree._is_leaf(node):
            self._remove_leaf(node)
            return
        if node.left and node.right:
            nxt = AvlTree._get_next(node)
            node.key = nxt.key
            node.value = nxt.value
            if self._is_leaf(nxt):
                self._remove_leaf(nxt)
            else:
                self._remove_one(nxt)
            self._rebalance(node)
        else:
            self._remove_one(node)

    def get(self, k):
        node = self._get_node(k)
        return node.value if node else -1

    def _get_node(self, k):
        if not self._tree:
            return None
        node = self._tree
        while node:
            if k < node.key:
                node = node.left
            elif node.key < k:
                node = node.right
            else:
                return node
        return None

    def get_at(self, pos):
        x = pos + 1
        node = self._tree
        while node:
            if x < node.num_left:
                node = node.left
            elif node.num_left < x:
                x -= node.num_left
                node = node.right
            else:
                return (node.key, node.value)
        raise IndexError("Out of ranges")

    @staticmethod
    def _is_left(node):
        return node.parent.left and node.parent.left == node

    @staticmethod
    def _is_leaf(node):
        return node.left is None and node.right is None

    def _rotate_right(self, node):
        if not node.parent:
            self._tree = node.left
            node.left.parent = None
        elif AvlTree._is_left(node):
            node.parent.left = node.left
            node.left.parent = node.parent
        else:
            node.parent.right = node.left
            node.left.parent = node.parent
        bk = node.left.right
        node.left.right = node
        node.parent = node.left
        node.left = bk
        if bk:
            bk.parent = node
        node.height = max(self.get_height(node.left), self.get_height(node.right)) + 1
        node.num_total = 1 + self.get_num_total(node.left) + self.get_num_total(node.right)
        node.num_left = 1 + self.get_num_total(node.left)

    def _rotate_left(self, node):
        if not node.parent:
            self._tree = node.right
            node.right.parent = None
        elif AvlTree._is_left(node):
            node.parent.left = node.right
            node.right.parent = node.parent
        else:
            node.parent.right = node.right
            node.right.parent = node.parent
        bk = node.right.left
        node.right.left = node
        node.parent = node.right
        node.right = bk
        if bk:
            bk.parent = node
        node.height = max(self.get_height(node.left), self.get_height(node.right)) + 1
        node.num_total = 1 + self.get_num_total(node.left) + self.get_num_total(node.right)
        node.num_left = 1 + self.get_num_total(node.left)

    @staticmethod
    def _get_next(node):
        if not node.right:
            return node.parent
        n = node.right
        while n.left:
            n = n.left
        return n


# -----------------------------------------------binary seacrh tree---------------------------------------
class SegmentTree1:
    def __init__(self, data, default=2**51, func=lambda a, b: a & b):
        """initialize the segment tree with data"""
        self._default = default
        self._func = func
        self._len = len(data)
        self._size = _size = 1 << (self._len - 1).bit_length()

        self.data = [default] * (2 * _size)
        self.data[_size:_size + self._len] = data
        for i in reversed(range(_size)):
            self.data[i] = func(self.data[i + i], self.data[i + i + 1])

    def __delitem__(self, idx):
        self[idx] = self._default

    def __getitem__(self, idx):
        return self.data[idx + self._size]

    def __setitem__(self, idx, value):
        idx += self._size
        self.data[idx] = value
        idx >>= 1
        while idx:
            self.data[idx] = self._func(self.data[2 * idx], self.data[2 * idx + 1])
            idx >>= 1

    def __len__(self):
        return self._len

    def query(self, start, stop):
        if start == stop:
            return self.__getitem__(start)
        stop += 1
        start += self._size
        stop += self._size

        res = self._default
        while start < stop:
            if start & 1:
                res = self._func(res, self.data[start])
                start += 1
            if stop & 1:
                stop -= 1
                res = self._func(res, self.data[stop])
            start >>= 1
            stop >>= 1
        return res

    def __repr__(self):
        return "SegmentTree({0})".format(self.data)


# -------------------game starts now----------------------------------------------------import math
class SegmentTree:
    def __init__(self, data, default=0, func=lambda a, b: a+b):
        """initialize the segment tree with data"""
        self._default = default
        self._func = func
        self._len = len(data)
        self._size = _size = 1 << (self._len - 1).bit_length()

        self.data = [default] * (2 * _size)
        self.data[_size:_size + self._len] = data
        for i in reversed(range(_size)):
            self.data[i] = func(self.data[i + i], self.data[i + i + 1])

    def __delitem__(self, idx):
        self[idx] = self._default

    def __getitem__(self, idx):
        return self.data[idx + self._size]

    def __setitem__(self, idx, value):
        idx += self._size
        self.data[idx] = value
        idx >>= 1
        while idx:
            self.data[idx] = self._func(self.data[2 * idx], self.data[2 * idx + 1])
            idx >>= 1

    def __len__(self):
        return self._len

    def query(self, start, stop):
        if start == stop:
            return self.__getitem__(start)
        stop += 1
        start += self._size
        stop += self._size

        res = self._default
        while start < stop:
            if start & 1:
                res = self._func(res, self.data[start])
                start += 1
            if stop & 1:
                stop -= 1
                res = self._func(res, self.data[stop])
            start >>= 1
            stop >>= 1
        return res

    def __repr__(self):
        return "SegmentTree({0})".format(self.data)


# -------------------------------iye ha chutiya zindegi-------------------------------------
class Factorial:
    def __init__(self, MOD):
        self.MOD = MOD
        self.factorials = [1, 1]
        self.invModulos = [0, 1]
        self.invFactorial_ = [1, 1]

    def calc(self, n):
        if n <= -1:
            print("Invalid argument to calculate n!")
            print("n must be non-negative value. But the argument was " + str(n))
            exit()
        if n < len(self.factorials):
            return self.factorials[n]
        nextArr = [0] * (n + 1 - len(self.factorials))
        initialI = len(self.factorials)
        prev = self.factorials[-1]
        m = self.MOD
        for i in range(initialI, n + 1):
            prev = nextArr[i - initialI] = prev * i % m
        self.factorials += nextArr
        return self.factorials[n]

    def inv(self, n):
        if n <= -1:
            print("Invalid argument to calculate n^(-1)")
            print("n must be non-negative value. But the argument was " + str(n))
            exit()
        p = self.MOD
        pi = n % p
        if pi < len(self.invModulos):
            return self.invModulos[pi]
        nextArr = [0] * (n + 1 - len(self.invModulos))
        initialI = len(self.invModulos)
        for i in range(initialI, min(p, n + 1)):
            next = -self.invModulos[p % i] * (p // i) % p
            self.invModulos.append(next)
        return self.invModulos[pi]

    def invFactorial(self, n):
        if n <= -1:
            print("Invalid argument to calculate (n^(-1))!")
            print("n must be non-negative value. But the argument was " + str(n))
            exit()
        if n < len(self.invFactorial_):
            return self.invFactorial_[n]
        self.inv(n)  # To make sure already calculated n^-1
        nextArr = [0] * (n + 1 - len(self.invFactorial_))
        initialI = len(self.invFactorial_)
        prev = self.invFactorial_[-1]
        p = self.MOD
        for i in range(initialI, n + 1):
            prev = nextArr[i - initialI] = (prev * self.invModulos[i % p]) % p
        self.invFactorial_ += nextArr
        return self.invFactorial_[n]


class Combination:
    def __init__(self, MOD):
        self.MOD = MOD
        self.factorial = Factorial(MOD)

    def ncr(self, n, k):
        if k < 0 or n < k:
            return 0
        k = min(k, n - k)
        f = self.factorial
        return f.calc(n) * f.invFactorial(max(n - k, k)) * f.invFactorial(min(k, n - k)) % self.MOD


# --------------------------------------iye ha combinations ka zindegi---------------------------------
def powm(a, n, m):
    if a == 1 or n == 0:
        return 1
    if n % 2 == 0:
        s = powm(a, n // 2, m)
        return s * s % m
    else:
        return a * powm(a, n - 1, m) % m


# --------------------------------------iye ha power ka zindegi---------------------------------
def sort_list(list1, list2):
    zipped_pairs = zip(list2, list1)

    z = [x for _, x in sorted(zipped_pairs)]

    return z


# --------------------------------------------------product----------------------------------------
def product(l):
    por = 1
    for i in range(len(l)):
        por *= l[i]
    return por


# --------------------------------------------------binary----------------------------------------
def binarySearchCount(arr, n, key):
    left = 0
    right = n - 1

    count = 0

    while (left <= right):
        mid = int((right + left) / 2)

        # Check if middle element is
        # less than or equal to key
        if (arr[mid] < key):
            count = mid + 1
            left = mid + 1

        # If key is smaller, ignore right half
        else:
            right = mid - 1

    return count


# --------------------------------------------------binary----------------------------------------
def countdig(n):
    c = 0
    while (n > 0):
        n //= 10
        c += 1
    return c
def binary(x, length):
    y = bin(x)[2:]
    return y if len(y) >= length else "0" * (length - len(y)) + y

def countGreater(arr, n, k):
    l = 0
    r = n - 1

    # Stores the index of the left most element
    # from the array which is greater than k
    leftGreater = n

    # Finds number of elements greater than k
    while (l <= r):
        m = int(l + (r - l) / 2)
        if (arr[m] >= k):
            leftGreater = m
            r = m - 1

        # If mid element is less than
        # or equal to k update l
        else:
            l = m + 1

    # Return the count of elements
    # greater than k
    return (n - leftGreater)

class TrieNode:
    def __init__(self):
        self.children = [None] * 26
        self.isEndOfWord = False
class Trie:
    def __init__(self):
        self.root = self.getNode()
    def getNode(self):
        return TrieNode()
    def _charToIndex(self, ch):
        return ord(ch) - ord('a')
    def insert(self, key):
        pCrawl = self.root
        length = len(key)
        for level in range(length):
            index = self._charToIndex(key[level])
            if not pCrawl.children[index]:
                pCrawl.children[index] = self.getNode()
            pCrawl = pCrawl.children[index]
        pCrawl.isEndOfWord = True
    def search(self, key):
        pCrawl = self.root
        length = len(key)
        for level in range(length):
            index = self._charToIndex(key[level])
            if not pCrawl.children[index]:
                return False
            pCrawl = pCrawl.children[index]
        return pCrawl != None and pCrawl.isEndOfWord
#-----------------------------------------trie---------------------------------
class Node:
    def __init__(self, data):
        self.data = data
        self.count=0
        self.left = None  # left node for 0
        self.right = None  # right node for 1
class BinaryTrie:
    def __init__(self):
        self.root = Node(0)
    def insert(self, pre_xor):
        self.temp = self.root
        for i in range(31, -1, -1):
            val = pre_xor & (1 << i)
            if val:
                if not self.temp.right:
                    self.temp.right = Node(0)
                self.temp = self.temp.right
                self.temp.count+=1
            if not val:
                if not self.temp.left:
                    self.temp.left = Node(0)
                self.temp = self.temp.left
                self.temp.count += 1
        self.temp.data = pre_xor
    def query(self, xor):
        self.temp = self.root
        for i in range(31, -1, -1):
            val = xor & (1 << i)
            if not val:
                if self.temp.left and self.temp.left.count>0:
                    self.temp = self.temp.left
                elif self.temp.right:
                    self.temp = self.temp.right
            else:
                if self.temp.right and self.temp.right.count>0:
                    self.temp = self.temp.right
                elif self.temp.left:
                    self.temp = self.temp.left
            self.temp.count-=1
        return xor ^ self.temp.data
# --------------------------------------------------binary-----------------------------------
for ik in range(int(input())):
    n,m=map(int,input().split())
    l=[]
    for i in range(n):
        st=input()
        l.append(st)
    l1=[]
    for j in range(n-1):
        st=input()
        l1.append(st)
    tot=set([i for i in range(n)])
    for i in range(m):
        ans=defaultdict(int)
        for j in range(n):
            ans[l[j][i]]+=1
        for j in range(n-1):
            ans[l1[j][i]]-=1
        t=""
        for j in ans:
            if ans[j]==1:
                t=j
                break
        s=set()
        for j in range(n):
            if l[j][i]==t:
                s.add(j)
        tot=tot&s
    print(l[max(tot)])