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.*;
  import java.util.StringTokenizer;
  
  public class CF_1602c{
      public static final void main(String[] args){
          Kattio io= new Kattio();
          int t= io.getInt();
          while(t-->0){
              int n= io.getInt(), k= io.getInt()+1; // n: [1..10], k:[1..10**9]
              int[] a= new int[n];
              for(int i=0; i<n; i++)
                  a[i]= power10(io.getInt());
              
              //err("powers=%s", Arrays.toString(a));
              long ans= 0;
              for(int remK= k, ai= 0; remK>0; ai++){
                  if(ai<n-1){ // not the highest denomination
                      int maxAi= a[ai+1]/a[ai]-1;
                      if(maxAi<remK){
                          ans+= (long)maxAi*a[ai];
                          remK-= maxAi;
                      }else{ //maxAi>=remK
                          ans+= (long)remK*a[ai];
                          remK= 0;
                      }
                  }else{
                      ans+= (long)remK*a[ai];
                      remK= 0;
                  }
              }
              io.println(ans);
          }
          io.close();
      }
  
      static int power10(int k){
          int ans= 1;
          while(k-->0) ans*= 10;
          return ans;
      }
  
      static void err(String format, Object... args){
          System.err.println(String.format(format, args));
      }    
      static class Kattio extends PrintWriter {
          private BufferedReader r;
          private String line, token;
          private StringTokenizer st;
      
          public Kattio(){this(System.in);}
          public Kattio(InputStream i){
          super(new BufferedOutputStream(System.out));
              r= new BufferedReader(new InputStreamReader(i));
          }
          public Kattio(InputStream i, OutputStream o){
          super(new BufferedOutputStream(o));
              r= new BufferedReader(new InputStreamReader(i));
          }
          public boolean isLineEnd(){
              return !st.hasMoreTokens();
          }
          public boolean hasMoreTokens(){
              return peekToken()!=null;
          }
          public int getInt(){
              return Integer.parseInt(nextToken());
          }
          public double getDouble(){ 
              return Double.parseDouble(nextToken());
          }
          public long getLong(){
              return Long.parseLong(nextToken());
          }
          public String getWord(){
              return nextToken();
          }
          private String peekToken(){
              if(token==null) try {
                  while(st==null || !st.hasMoreTokens()) {
                      line= r.readLine();
                      if(line==null) return null;
                      st= new StringTokenizer(line);
                  }
                  token= st.nextToken();
              }catch(IOException e){}
              return token;
          }
          private String nextToken() {
              String ans= peekToken();
              token= null;
              return ans;
          }
      }    
  }