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.*;

public class Codeforces {

    public static class FastWriter {
        private static final int BUF_SIZE = 1 << 13;
        private final byte[] buf = new byte[BUF_SIZE];
        private final OutputStream out;
        private int ptr = 0;

        private FastWriter() {
            out = null;
        }

        public FastWriter(OutputStream os) {
            this.out = os;
        }

        public FastWriter(String path) {
            try {
                this.out = new FileOutputStream(path);
            } catch (FileNotFoundException e) {
                throw new RuntimeException("FastWriter");
            }
        }

        public FastWriter write(byte b) {
            buf[ptr++] = b;
            if (ptr == BUF_SIZE) innerflush();
            return this;
        }

        public FastWriter write(char c) {
            return write((byte) c);
        }

        public FastWriter write(char[] s) {
            for (char c : s) {
                buf[ptr++] = (byte) c;
                if (ptr == BUF_SIZE) innerflush();
            }
            return this;
        }

        public FastWriter write(String s) {
            s.chars().forEach(c -> {
                buf[ptr++] = (byte) c;
                if (ptr == BUF_SIZE) innerflush();
            });
            return this;
        }

        private static int countDigits(int l) {
            if (l >= 1000000000) return 10;
            if (l >= 100000000) return 9;
            if (l >= 10000000) return 8;
            if (l >= 1000000) return 7;
            if (l >= 100000) return 6;
            if (l >= 10000) return 5;
            if (l >= 1000) return 4;
            if (l >= 100) return 3;
            if (l >= 10) return 2;
            return 1;
        }

        public FastWriter write(int x) {
            if (x == Integer.MIN_VALUE) {
                return write((long) x);
            }
            if (ptr + 12 >= BUF_SIZE) innerflush();
            if (x < 0) {
                write((byte) '-');
                x = -x;
            }
            int d = countDigits(x);
            for (int i = ptr + d - 1; i >= ptr; i--) {
                buf[i] = (byte) ('0' + x % 10);
                x /= 10;
            }
            ptr += d;
            return this;
        }

        private static int countDigits(long l) {
            if (l >= 1000000000000000000L) return 19;
            if (l >= 100000000000000000L) return 18;
            if (l >= 10000000000000000L) return 17;
            if (l >= 1000000000000000L) return 16;
            if (l >= 100000000000000L) return 15;
            if (l >= 10000000000000L) return 14;
            if (l >= 1000000000000L) return 13;
            if (l >= 100000000000L) return 12;
            if (l >= 10000000000L) return 11;
            if (l >= 1000000000L) return 10;
            if (l >= 100000000L) return 9;
            if (l >= 10000000L) return 8;
            if (l >= 1000000L) return 7;
            if (l >= 100000L) return 6;
            if (l >= 10000L) return 5;
            if (l >= 1000L) return 4;
            if (l >= 100L) return 3;
            if (l >= 10L) return 2;
            return 1;
        }

        public FastWriter write(long x) {
            if (x == Long.MIN_VALUE) {
                return write("" + x);
            }
            if (ptr + 21 >= BUF_SIZE) innerflush();
            if (x < 0) {
                write((byte) '-');
                x = -x;
            }
            int d = countDigits(x);
            for (int i = ptr + d - 1; i >= ptr; i--) {
                buf[i] = (byte) ('0' + x % 10);
                x /= 10;
            }
            ptr += d;
            return this;
        }

        public FastWriter write(double x, int precision) {
            if (x < 0) {
                write('-');
                x = -x;
            }
            x += Math.pow(10, -precision) / 2;
            //		if(x < 0){ x = 0; }
            write((long) x).write(".");
            x -= (long) x;
            for (int i = 0; i < precision; i++) {
                x *= 10;
                write((char) ('0' + (int) x));
                x -= (int) x;
            }
            return this;
        }

        public FastWriter writeln(char c) {
            return write(c).writeln();
        }

        public FastWriter writeln(int x) {
            return write(x).writeln();
        }

        public FastWriter writeln(long x) {
            return write(x).writeln();
        }

        public FastWriter writeln(double x, int precision) {
            return write(x, precision).writeln();
        }

        public FastWriter write(int... xs) {
            boolean first = true;
            for (int x : xs) {
                if (!first) write(' ');
                first = false;
                write(x);
            }
            return this;
        }

        public FastWriter write(long... xs) {
            boolean first = true;
            for (long x : xs) {
                if (!first) write(' ');
                first = false;
                write(x);
            }
            return this;
        }

        public FastWriter writeln() {
            return write((byte) '\n');
        }

        public FastWriter writeln(int... xs) {
            return write(xs).writeln();
        }

        public FastWriter writeln(long... xs) {
            return write(xs).writeln();
        }

        public FastWriter writeln(char[] line) {
            return write(line).writeln();
        }

        public FastWriter writeln(char[]... map) {
            for (char[] line : map) write(line).writeln();
            return this;
        }

        public FastWriter writeln(String s) {
            return write(s).writeln();
        }

        private void innerflush() {
            try {
                out.write(buf, 0, ptr);
                ptr = 0;
            } catch (IOException e) {
                throw new RuntimeException("innerflush");
            }
        }

        public void flush() {
            innerflush();
            try {
                out.flush();
            } catch (IOException e) {
                throw new RuntimeException("flush");
            }
        }

        public FastWriter print(byte b) {
            return write(b);
        }

        public FastWriter print(char c) {
            return write(c);
        }

        public FastWriter print(char[] s) {
            return write(s);
        }

        public FastWriter print(String s) {
            return write(s);
        }

        public FastWriter print(int x) {
            return write(x);
        }

        public FastWriter print(long x) {
            return write(x);
        }

        public FastWriter print(double x, int precision) {
            return write(x, precision);
        }

        public FastWriter println(char c) {
            return writeln(c);
        }

        public FastWriter println(int x) {
            return writeln(x);
        }

        public FastWriter println(long x) {
            return writeln(x);
        }

        public FastWriter println(double x, int precision) {
            return writeln(x, precision);
        }

        public FastWriter print(int... xs) {
            return write(xs);
        }

        public FastWriter print(long... xs) {
            return write(xs);
        }

        public FastWriter println(int... xs) {
            return writeln(xs);
        }

        public FastWriter println(long... xs) {
            return writeln(xs);
        }

        public FastWriter println(char[] line) {
            return writeln(line);
        }

        public FastWriter println(char[]... map) {
            return writeln(map);
        }

        public FastWriter println(String s) {
            return writeln(s);
        }

        public FastWriter println() {
            return writeln();
        }
    }


    static final class InputReader {
        private final InputStream stream;
        private final byte[] buf = new byte[1024];
        private int curChar;
        private int numChars;

        public InputReader(InputStream stream) {
            this.stream = stream;
        }

        private int read() throws IOException {
            if (curChar >= numChars) {
                curChar = 0;
                numChars = stream.read(buf);
                if (numChars <= 0) {
                    return -1;
                }
            }
            return buf[curChar++];
        }

        public final int readInt() throws IOException {
            return (int) readLong();
        }

        public final long readLong() throws IOException {
            int c = read();
            while (isSpaceChar(c)) {
                c = read();
                if (c == -1) throw new IOException();
            }
            boolean negative = false;
            if (c == '-') {
                negative = true;
                c = read();
            }
            long res = 0;
            do {
                res *= 10;
                res += c - '0';
                c = read();
            } while (!isSpaceChar(c));
            return negative ? -res : res;
        }

        public final int[] readIntArray(int size) throws IOException {
            int[] array = new int[size];
            for (int i = 0; i < size; i++) {
                array[i] = readInt();
            }
            return array;
        }

        public final long[] readLongArray(int size) throws IOException {
            long[] array = new long[size];
            for (int i = 0; i < size; i++) {
                array[i] = readLong();
            }
            return array;
        }

        public final String readString() throws IOException {
            int c = read();
            while (isSpaceChar(c)) {
                c = read();
            }
            StringBuilder res = new StringBuilder();
            do {
                res.append((char) c);
                c = read();
            } while (!isSpaceChar(c));
            return res.toString();
        }

        private boolean isSpaceChar(int c) {
            return c == ' ' || c == '\n' || c == '\r' || c == '\t' || c == -1;
        }
    }

    static long mulmod(long a, long b,
                       long mod) {
        long res = 0; // Initialize result
        a = a % mod;
        while (b > 0) {
            // If b is odd, add 'a' to result
            if (b % 2 == 1) {
                res = (res + a) % mod;
            }

            // Multiply 'a' with 2
            a = (a * 2) % mod;

            // Divide b by 2
            b /= 2;
        }

        // Return result
        return res % mod;
    }

    static long pow(long a, long b, long MOD) {
        long x = 1, y = a;
        while (b > 0) {
            if (b % 2 == 1) {
                x = (x * y);
                if (x > MOD) x %= MOD;
            }
            y = (y * y);
            if (y > MOD) y %= MOD;
            b /= 2;
        }
        return x;
    }

    static long[] f = new long[200001];

    static long InverseEuler(long n, long MOD) {
        return pow(n, MOD - 2, MOD);
    }

    static long C(int n, int r, long MOD) {

        return (f[n] * ((InverseEuler(f[r], MOD) * InverseEuler(f[n - r], MOD)) % MOD)) % MOD;
    }


    static int[] h = {0, 0, -1, 1};
    static int[] v = {1, -1, 0, 0};


    public static class Pair {
        public int a;

        public int b;

        @Override
        public boolean equals(Object o) {
            if (this == o) return true;
            if (o == null || getClass() != o.getClass()) return false;
            Pair pair = (Pair) o;
            return a == pair.a &&
                    b == pair.b;
        }

        @Override
        public int hashCode() {
            return Objects.hash(a, b);
        }

        public Pair(int a, int b) {
            this.a = a;
            this.b = b;
        }
    }

    static class Pair2 {
        public long cost;
        int node;

        public Pair2(long cos, int node) {
            this.cost = cos;
            this.node = node;
        }
    }

    static long compute_hash(String s) {
        int p = 31;
        int m = 1000000007;
        long hash_value = 0;
        long p_pow = 1;
        for (int i = 0; i < s.length(); ++i) {
            char c = s.charAt(i);
            hash_value = (hash_value + (c - 'a' + 1) * p_pow) % m;
            p_pow = (p_pow * p) % m;
        }
        return hash_value;
    }

    public static class SegmentTree {
        long[][] tree;
        int n;

        public SegmentTree(int[] nodes) {
            tree = new long[nodes.length * 4][2];
            n = nodes.length;
            build(0, n - 1, 0, nodes);

        }

        private void build(int l, int r, int pos, int[] nodes) {
            if (l == r) {
                tree[pos][0] = nodes[l];
                tree[pos][1] = l;
                return;
            }
            int mid = (l + r) / 2;
            build(l, mid, 2 * pos + 1, nodes);
            build(mid + 1, r, 2 * pos + 2, nodes);
            if (tree[2 * pos + 1][0] > tree[2 * pos + 2][0]) {
                tree[pos][1] = tree[2 * pos + 1][1];
            } else {
                tree[pos][1] = tree[2 * pos + 2][1];
            }
            tree[pos][0] = Math.max(tree[2 * pos + 1][0], tree[2 * pos + 2][0]);
        }

        //        public void update(int pos, int val) {
        //            updateUtil(0, n - 1, 0, pos, val);
        //        }

        public long[] get(int l, int r) {
            return getUtil(0, n - 1, 0, l, r);
        }

        private long[] getUtil(int l, int r, int pos, int ql, int qr) {
            if (ql > r || qr < l) {
                return new long[]{-1, -1};
            }
            if (l >= ql && r <= qr) {
                return tree[pos];
            }

            int mid = (l + r) / 2;
            long[] left = getUtil(l, mid, 2 * pos + 1, ql, qr);
            long[] right = getUtil(mid + 1, r, 2 * pos + 2, ql, qr);
            long choice = right[1];
            if (left[0] > right[0]) choice = left[1];
            return new long[]{Math.max(left[0], right[0]), choice};

        }

        //        private void updateUtil(int l, int r, int pos, int i, int val) {
        //            if (i < l || i > r) {
        //                return;
        //            }
        //            if (l == r) {
        //                tree[pos] = val;
        //                return;
        //            }
        //            int mid = (l + r) / 2;
        //            updateUtil(l, mid, 2 * pos + 1, i, val);
        //            updateUtil(mid + 1, r, 2 * pos + 2, i, val);
        //            tree[pos] = tree[2 * pos + 1] + tree[2 * pos + 2];
        //        }
    }

    static int counter = 0;
    static int[] rIn;
    static int[] rOut;
    static int[] lIn;
    static int[] lOut;
    private static int[] flatten;
    private static int[] lFlatten;
    static long answer = 0;

    static int VISITED = 1;
    static int VISITING = 2;

    static int[] DIRX = new int[]{0, 0, 1, -1};
    static int[] DIRY = new int[]{1, -1, 0, 0};

    public static class Pair22 {
        int num, pos;

        public Pair22(int x, int y) {
            this.num = x;
            this.pos = y;
        }
    }

    public static long sumofdig(long n) {
        long sum = 0;
        while (n > 0) {
            sum += n % 10;
            n /= 10;
        }
        return sum;
    }

    public static class DK {
        int D, K;

        public DK(int d, int k) {
            D = d;
            K = k;
        }

        @Override
        public boolean equals(Object o) {
            if (this == o) return true;
            if (o == null || getClass() != o.getClass()) return false;
            DK dk = (DK) o;
            return D == dk.D &&
                    K == dk.K;
        }

        @Override
        public int hashCode() {
            return Objects.hash(D, K);
        }
    }

    public static void main(String[] args) throws Exception {
        //https://i...content-available-to-author-only...e.com/ebRGa6
        InputReader in = new InputReader(System.in);

        FastWriter out = new FastWriter(System.out);


//
//        f[0] = 1;
//        f[1] = 1;
//        for (int i = 2; i < 200001; ++i) {
//            f[i] = f[i-1] * i;
//            f[i] %= 1000000007;
//        }
        int t = in.readInt();


        while (t-- > 0) {
            int n = in.readInt();
            int m = in.readInt();
            int[][] count = new int[m][26];

            for (int i = 0; i < n; ++i) {
                String s = in.readString();
                for (int j = 0; j < m; ++j) {
                    count[j][s.charAt(j) - 'a']++;
                }
            }
            int[][] count2 = new int[m][26];

            for (int i = 0; i < n-1; ++i) {
                String s = in.readString();
                for (int j = 0; j < m; ++j) {
                    count2[j][s.charAt(j) - 'a']++;
                }
            }
            StringBuilder ans = new StringBuilder();
            for (int i = 0; i < m; ++i) {
                for (int j = 0; j < 26; ++j) {
                    if (count[i][j] != count2[i][j]) {
                        ans.append((char) (j + 'a'));
                        break;
                    }
                }
            }

            System.out.println(ans.toString());
            System.out.flush();



        }

    }

    private static void printBit(long maxBitSet, int m) {
        StringBuilder ans = new StringBuilder();

        while (maxBitSet > 0) {
            if (maxBitSet % 2 == 1) {
                ans.append("1");
            } else {
                ans.append("0");
            }
            maxBitSet /= 2;
        }

        for (int i = m - 1; i >= 0; --i) {
            if (i <= ans.length() - 1)
                System.out.print(ans.charAt(i));
            else
                System.out.print(0);
        }
        System.out.println();
    }

    private static void solvedd(int[] arr, int left, int right, int[] ans, int depth) {

        if (left > right) return;
        int maxInd = left;
        for (int i = left; i <= right; ++i) {
            if (arr[i] > arr[maxInd]) {
                maxInd = i;
            }
        }

        ans[maxInd] = depth;

        solvedd(arr, left, maxInd - 1, ans, depth + 1);
        solvedd(arr, maxInd + 1, right, ans, depth + 1);

    }


    private static void solved(List<List<Integer>> g, int node, int[][] dp, int last, int[] a) {

        int donttake = 0;
        int take = 0;
        for (int i = 0; i < g.get(node).size(); ++i) {
            int ntb = g.get(node).get(i);

            if (ntb != last) {
                solved(g, ntb, dp, node, a);
                donttake += Math.max(dp[ntb][0], dp[ntb][1]);
                take += dp[ntb][1];
            }
        }
        dp[node][0] = a[node] + take;
        dp[node][1] = donttake;
    }


    private static boolean solve(int n, List<Integer> nums, int cur, int pos, Boolean[][] dp) {
        if (cur > n) return false;
        if (cur == n) return true;
        if (pos >= nums.size()) return false;

        if (dp[cur][pos] != null) {
            return dp[cur][pos];
        }
        boolean without = solve(n, nums, cur, pos + 1, dp);
        boolean with = false;
        int ogcur = cur;
        for (int i = 1; i < 12; ++i) {
            with |= solve(n, nums, cur + nums.get(pos), pos + 1, dp);
            cur += nums.get(pos);
        }

        return dp[ogcur][pos] = with | without;
    }

//    private static Pair22 dfss(List<LinkedHashSet<Integer>> g, int node, HashSet<Integer> vis, int[] dis, int[] dis2) {
//        if (vis.contains(node)) return new Pair22(dis[node], dis2[node], -1);
//        vis.add(node);
//        int min = dis[node];
//        for (Integer ntb : g.get(node)) {
//            if (dis[ntb] > dis[node])
//                dfss(g, ntb, vis, dis, dis2);
//            if (dis[ntb] <= dis[node]) {
//                min = Math.min(min, dis[ntb]);
//            } else {
//                min = Math.min(min, dis2[ntb]);
//            }
//        }
//        //        if (dis)
//        dis2[node] = min;
//        return new Pair22(dis[node], min, -1);
//    }


    private static int dfs(HashMap<Pair, TreeSet<Pair>> grid, int x, int y, int ti, HashSet<Pair> vis, int r, int startX, int startY) {
        //        System.out.println(x + "  " + y);
        int taken = ti - Math.abs(startX - x) - Math.abs(startY - y);
        if (taken < 0) return 0;
        if (x < 0 || y < 0 || x > r || y > r) return 0;
        if (vis.contains(new Pair(x, y))) return 0;
        int max = 0;

        if (grid.containsKey(new Pair(x, y))) {
            TreeSet<Pair> times = grid.get(new Pair(x, y));
            for (Pair t : times) {
                if (t.a <= taken) {
                    max = Math.max(t.b, max);
                } else break;
            }
        }
        vis.add(new Pair(x, y));
        max = Math.max(dfs(grid, x + 1, y, ti, vis, r, startX, startY), max);
        max = Math.max(dfs(grid, x, y + 1, ti, vis, r, startX, startY), max);
        max = Math.max(dfs(grid, x - 1, y, ti, vis, r, startX, startY), max);
        max = Math.max(dfs(grid, x, y - 1, ti, vis, r, startX, startY), max);
        return max;
    }

    private static int solver(int[] nums, int pos, int[] dp) {
        if (pos >= nums.length) return 0;
        if (dp[pos] != Integer.MAX_VALUE) return dp[pos];
        int min = solver(nums, pos + 2, dp) + nums[pos];
        min = Math.min(solver(nums, pos + 3, dp) + nums[pos], min);
        if (pos + 1 < nums.length) min = Math.min(min, nums[pos] + nums[pos + 1] + solver(nums, pos + 3, dp));
        if (pos + 1 < nums.length) min = Math.min(min, nums[pos] + nums[pos + 1] + solver(nums, pos + 4, dp));

        //        System.out.println(pos + " " + min);
        return dp[pos] = min;
    }


    static int countFreq(String pattern, String text) {
        int m = pattern.length();
        int n = text.length();
        int res = 0;

        for (int i = 0; i <= n - m; i++) {
            int j;
            for (j = 0; j < m; j++) {
                if (text.charAt(i + j) != pattern.charAt(j)) {
                    break;
                }
            }
            if (j == m) {
                res++;
                j = 0;
            }
        }
        return res;
    }

    private static void dfsR(List<List<Integer>> g, int node, int[] v) {
        rIn[node] = counter;
        flatten[counter++] = v[node];

        for (int i = 0; i < g.get(node).size(); ++i) {
            dfsR(g, g.get(node).get(i), v);
        }

        rOut[node] = counter;
        flatten[counter++] = v[node] * -1;
    }

    private static void dfsL(List<List<Integer>> g, int node, int[] v) {
        lIn[node] = counter;
        lFlatten[counter++] = v[node];

        for (int i = 0; i < g.get(node).size(); ++i) {
            dfsL(g, g.get(node).get(i), v);
        }

        lOut[node] = counter;
        lFlatten[counter++] = v[node] * -1;

        TreeMap<String, Integer> map = new TreeMap<>();
    }


    private static void preprocess(int pos, int[][] pre, List<List<Integer>> tree, int[] traverse, int depth, int last, int[] tin, int[] tout) {
        tin[pos] = counter++;
        traverse[depth] = pos;

        for (int i = 0; depth - (1 << i) >= 0; ++i) {
            pre[pos][i] = traverse[depth - (1 << i)];
        }

        for (int i = 0; i < tree.get(pos).size(); ++i) {
            if (tree.get(pos).get(i) != last)
                preprocess(tree.get(pos).get(i), pre, tree, traverse, depth + 1, pos, tin, tout);
        }
        tout[pos] = counter++;
    }

    static long gcd(long a, long b) {

        while (b != 0) {
            long t = a;
            a = b;
            b = t % b;
        }
        return a;
    }

    static long lcm(long a, long b) {

        return a * b / gcd(a, b);
    }


    static boolean submit = true;

    static void debug(String s) {
        if (!submit)
            System.out.println(s);
    }

    static void debug(int s) {
        LinkedHashSet<Integer> exist = new LinkedHashSet<>();
            /*

            4 2 3 _ 2 4 3 _
             */
    }


}