description: In Berland, n different types of banknotes are used. Banknotes of the i-th type have denomination 10^{a_i} burles (burles are the currency used in Berland); the denomination of banknotes of the first type is exactly 1.
  
  Let's denote f(s) as the minimum number of banknotes required to represent exactly s burles. For example, if the denominations of banknotes used in Berland are 1, 10 and 100, then f(59) = 14: 9 banknotes with denomination of 1 burle and 5 banknotes with denomination of 10 burles can be used to represent exactly 9 ⋅ 1 + 5 ⋅ 10 = 59 burles, and there's no way to do it with fewer banknotes.
  
  For a given integer k, find the minimum positive number of burles s that cannot be represented with k or fewer banknotes (that is, f(s) > k).
  
  Input
  
  The first line contains a single integer t (1 ≤ t ≤ 10^4) — number of test cases.
  
  The first line of each test case contains two integers n and k (1 ≤ n ≤ 10; 1 ≤ k ≤ 10^9).
  
  The next line contains n integers a_1, a_2, ..., a_n (0 = a_1 < a_2 < ... < a_n ≤ 9).
  
  Output
  
  For each test case, print one integer — the minimum positive number of burles s that cannot be represented with k or fewer banknotes.
  
  Example
  
  Input
  
  
  4
  3 13
  0 1 2
  2 777
  0 4
  3 255
  0 1 3
  10 1000000000
  0 1 2 3 4 5 6 7 8 9
  
  
  Output
  
  
  59
  778
  148999
  999999920999999999
solution: import java.util.*;
  import java.io.*;
  
  public class C {
      static StringBuilder sb;
      static long fact[];
      static long mod = (long) (1e9 + 7);
      static int[] arr = { 0, 1, 11, 111, 1111, 11111, 111111, 1111111, 11111111, 111111111, 1111111111 };
  
      static void solve(int[] arr, int n, long k) {
          long[] coins = new long[arr.length];
          for (int i = 0; i < n; i++) {
              coins[i] = p(10, arr[i]);
          }
  
          k++;
  
          long s = 0;
          for (int i = 0; i < n - 1; i++) {
              long maxUsagePossible = Math.min((coins[i + 1] / coins[i]) - 1, k);
              k -= maxUsagePossible;
              s += maxUsagePossible * coins[i];
  
          }
  
          s += coins[n - 1] * k;
  
          sb.append(s + "\n");
  
      }
  
      public static void main(String[] args) {
          sb = new StringBuilder();
          int test = i();
          while (test-- > 0) {
              int n = i();
              long k = l();
              int[] arr = readArray(n);
              solve(arr, n, k);
          }
          out.printLine(sb);
          out.flush();
          out.close();
  
      }
  
      /*
       * fact=new long[(int)1e6+10]; fact[0]=fact[1]=1; for(int i=2;i<fact.length;i++)
       * { fact[i]=((long)(i%mod)1L(long)(fact[i-1]%mod))%mod; }
       */
      // **************NCR%P******************
  
      static long p(long x, long y)// POWER FXN //
      {
          if (y == 0)
              return 1;
  
          long res = 1;
          while (y > 0) {
              if (y % 2 == 1) {
                  res = (res * x) % mod;
                  y--;
              }
  
              x = (x * x) % mod;
              y = y / 2;
  
          }
          return res;
      }
  
      static long ncr(int n, int r) {
          if (r > n)
              return (long) 0;
  
          long res = fact[n] % mod;
          // System.out.println(res);
          res = ((long) (res % mod) * (long) (p(fact[r], mod - 2) % mod)) % mod;
          res = ((long) (res % mod) * (long) (p(fact[n - r], mod - 2) % mod)) % mod;
          // System.out.println(res);
          return res;
  
      }
  
      // **************END******************
  
      // *************Disjoint set
      // union*********//
  
      // ***************PRIME FACTORIZE
      // ***********************************//
      static TreeMap<Integer, Integer> prime(long n) {
          TreeMap<Integer, Integer> h = new TreeMap<>();
          long num = n;
          for (int i = 2; i <= Math.sqrt(num); i++) {
              if (n % i == 0) {
                  int nt = 0;
                  while (n % i == 0) {
                      n = n / i;
                      nt++;
                  }
                  h.put(i, nt);
              }
          }
          if (n != 1)
              h.put((int) n, 1);
          return h;
  
      }
  
      // *****CLASS PAIR
      // *************************************************
      static class Pair implements Comparable<Pair> {
          int x;
          long y;
  
          Pair(int x, long y) {
              this.x = x;
              this.y = y;
          }
  
          public int compareTo(Pair o) {
              return (int) (this.y - o.y);
  
          }
  
      }
      // *****CLASS PAIR
      // ***************************************************
  
      static class InputReader {
          private InputStream stream;
          private byte[] buf = new byte[1024];
          private int curChar;
          private int numChars;
          private SpaceCharFilter filter;
  
          public InputReader(InputStream stream) {
              this.stream = stream;
          }
  
          public int read() {
              if (numChars == -1)
                  throw new InputMismatchException();
              if (curChar >= numChars) {
                  curChar = 0;
                  try {
                      numChars = stream.read(buf);
                  } catch (IOException e) {
                      throw new InputMismatchException();
                  }
                  if (numChars <= 0)
                      return -1;
              }
              return buf[curChar++];
          }
  
          public int Int() {
              int c = read();
              while (isSpaceChar(c))
                  c = read();
              int sgn = 1;
              if (c == '-') {
                  sgn = -1;
                  c = read();
              }
              int res = 0;
              do {
                  if (c < '0' || c > '9')
                      throw new InputMismatchException();
                  res *= 10;
                  res += c - '0';
                  c = read();
              } while (!isSpaceChar(c));
              return res * sgn;
          }
  
          public String String() {
              int c = read();
              while (isSpaceChar(c))
                  c = read();
              StringBuilder res = new StringBuilder();
              do {
                  res.appendCodePoint(c);
                  c = read();
              } while (!isSpaceChar(c));
              return res.toString();
          }
  
          public boolean isSpaceChar(int c) {
              if (filter != null)
                  return filter.isSpaceChar(c);
              return c == ' ' || c == '\n' || c == '\r' || c == '\t' || c == -1;
          }
  
          public String next() {
              return String();
          }
  
          public interface SpaceCharFilter {
              public boolean isSpaceChar(int ch);
          }
      }
  
      static class OutputWriter {
          private final PrintWriter writer;
  
          public OutputWriter(OutputStream outputStream) {
              writer = new PrintWriter(new BufferedWriter(new OutputStreamWriter(outputStream)));
          }
  
          public OutputWriter(Writer writer) {
              this.writer = new PrintWriter(writer);
          }
  
          public void print(Object... objects) {
              for (int i = 0; i < objects.length; i++) {
                  if (i != 0)
                      writer.print(' ');
                  writer.print(objects[i]);
              }
          }
  
          public void printLine(Object... objects) {
              print(objects);
              writer.println();
          }
  
          public void close() {
              writer.close();
          }
  
          public void flush() {
              writer.flush();
          }
      }
  
      static InputReader in = new InputReader(System.in);
      static OutputWriter out = new OutputWriter(System.out);
  
      public static long[] sortlong(long[] a2) {
          int n = a2.length;
          ArrayList<Long> l = new ArrayList<>();
          for (long i : a2)
              l.add(i);
          Collections.sort(l);
          for (int i = 0; i < l.size(); i++)
              a2[i] = l.get(i);
          return a2;
      }
  
      public static int[] sortint(int[] a2) {
          int n = a2.length;
          ArrayList<Integer> l = new ArrayList<>();
          for (int i : a2)
              l.add(i);
          Collections.sort(l);
          for (int i = 0; i < l.size(); i++)
              a2[i] = l.get(i);
          return a2;
      }
  
      public static long pow(long x, long y) {
          long res = 1;
          while (y > 0) {
              if (y % 2 != 0) {
                  res = (res * x);// % modulus;
                  y--;
  
              }
              x = (x * x);// % modulus;
              y = y / 2;
          }
          return res;
      }
  
      // GCD___+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
      public static long gcd(long x, long y) {
          if (x == 0)
              return y;
          else
              return gcd(y % x, x);
      }
      // ******LOWEST COMMON MULTIPLE
      // *********************************************
  
      public static long lcm(long x, long y) {
          return (x * (y / gcd(x, y)));
      }
  
      // INPUT
      // PATTERN********************************************************
      public static int i() {
          return in.Int();
      }
  
      public static long l() {
          String s = in.String();
          return Long.parseLong(s);
      }
  
      public static String s() {
          return in.String();
      }
  
      public static int[] readArray(int n) {
          int A[] = new int[n];
          for (int i = 0; i < n; i++) {
              A[i] = i();
          }
          return A;
      }
  
      public static long[] readArray(long n) {
          long A[] = new long[(int) n];
          for (int i = 0; i < n; i++) {
              A[i] = l();
          }
          return A;
      }
  
  }