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.lang.reflect.Array;
  import java.util.*;
  import java.io.*;
  import java.util.concurrent.atomic.AtomicReferenceArray;
  
  
  public class Main {
      static class Pair<U, V> {
          public final U first;
          public final V second;
  
          public Pair(U first, V second) {
              this.first = first;
              this.second = second;
          }
  
          public static <U, V> Pair<U, V> of(U a, V b) {
              return new Pair<>(a, b);
          }
  
          final int a = 2;
  
          @Override
          public int hashCode() {
              int hash = 5;
              hash = 17 * hash + this.a;
              return hash;
          }
  
          @Override
          public boolean equals(Object obj) {
              if (obj == null) {
                  return false;
              }
              if (getClass() != obj.getClass()) {
                  return false;
              }
              final Pair other = (Pair) obj;
              if (this.a != other.a) {
                  return false;
              }
              return true;
          }
      }
  
      //----------------------------------------------------------------------------------------------
      public static void main(String hi[]) throws Exception {
          FastReader sc = new FastReader();
          int t = sc.nextInt();
          while (t-- > 0) {
              int n =  sc.nextInt();
              long k = 1L * sc.nextLong();
              int[] a = new int[n];
              for(int i=0;i<n;i++)
                  a[i]=sc.nextInt();
              Arrays.sort(a);
                  long[] arr = new long[n];
                  for(int i=0;i<n;i++)
                  {
                      int temp=a[i];
                      long x=1;
                      while(temp>0)
                      {
                          x*=10;
                          temp--;
                      }
                      arr[i]=x;
                  }
  
  //                for(int i=0;i<n;i++)
  //                    System.out.print(arr[i]+" ");
  //            System.out.println();
                  k++;
                  long ans=0L;
                  for(int i=0;i<n-1;i++)
                  {
                      long x=Math.min((arr[i+1]-arr[i])/arr[i],k);
  
                      ans+=x*arr[i];
                      k-=x;
  //                    System.out.println(ans+" "+k+" "+x);
                      if(k==0)
                          break;
                  }
                  if(k>0)
                  {
                      ans+=k*arr[n-1];
                  }
              System.out.println(ans);
          }
      }
  
  
      static class FastReader {
          BufferedReader br;
          StringTokenizer st;
  
          public FastReader() {
              br = new BufferedReader(new
                      InputStreamReader(System.in));
          }
  
          String next() {
              while (st == null || !st.hasMoreElements()) {
                  try {
                      st = new StringTokenizer(br.readLine());
                  } catch (IOException e) {
                      e.printStackTrace();
                  }
              }
              return st.nextToken();
          }
  
          int nextInt() {
              return Integer.parseInt(next());
          }
  
          long nextLong() {
              return Long.parseLong(next());
          }
  
          double nextDouble() {
              return Double.parseDouble(next());
          }
  
          String nextLine() {
              String str = "";
              try {
                  str = br.readLine();
              } catch (IOException e) {
                  e.printStackTrace();
              }
              return str;
  
          }
      }
  }
  
  