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.io.OutputStream;
  import java.io.IOException;
  import java.io.InputStream;
  import java.io.PrintWriter;
  import java.io.IOException;
  import java.io.InputStreamReader;
  import java.util.StringTokenizer;
  import java.io.BufferedReader;
  import java.io.FileReader;
  import java.io.InputStream;
  
  /**
   * Built using CHelper plug-in
   * Actual solution is at the top
   *
   * @author Khater
   */
  public class Main {
      public static void main(String[] args) {
          InputStream inputStream = System.in;
          OutputStream outputStream = System.out;
          Scanner in = new Scanner(inputStream);
          PrintWriter out = new PrintWriter(outputStream);
          CBanknotes solver = new CBanknotes();
          solver.solve(1, in, out);
          out.close();
      }
  
      static class CBanknotes {
          public void solve(int testNumber, Scanner sc, PrintWriter pw) {
              int t = 1;
              t = sc.nextInt();
              long[] pow = new long[10];
              long p = 1;
              for (int i = 0; i < 10; i++) {
                  pow[i] = p;
                  p *= 10;
              }
              while (t-- > 0) {
                  int n = sc.nextInt();
                  long k = sc.nextLong() + 1;
                  int[] arr = sc.nextIntArr(n);
                  String ans = "";
                  for (int i = 0; i < n - 1 && k != 0; i++) {
                      int dif = arr[i + 1] - arr[i];
                      long all = pow[dif] - 1;
                      long min = Math.min(all, k);
                      k -= min;
                      ans = (min) + ans;
                  }
                  if (k != 0)
                      pw.println(k + ans);
                  else pw.println(ans);
              }
  
          }
  
      }
  
      static class Scanner {
          StringTokenizer st;
          BufferedReader br;
  
          public Scanner(FileReader r) {
              br = new BufferedReader(r);
          }
  
          public Scanner(InputStream s) {
              br = new BufferedReader(new InputStreamReader(s));
          }
  
          public String next() {
              while (st == null || !st.hasMoreTokens()) {
                  try {
                      st = new StringTokenizer(br.readLine());
                  } catch (IOException e) {
                      throw new RuntimeException(e);
                  }
              }
              return st.nextToken();
          }
  
          public int nextInt() {
              return Integer.parseInt(next());
          }
  
          public long nextLong() {
              return Long.parseLong(next());
          }
  
          public int[] nextIntArr(int n) {
              try {
                  int[] a = new int[n];
                  for (int i = 0; i < n; i++)
                      a[i] = nextInt();
                  return a;
              } catch (Exception e) {
                  throw new RuntimeException(e);
              }
  
          }
  
      }
  }
  
  