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.*;
  import java.io.BufferedReader;
  import java.io.IOException;
  import java.io.InputStreamReader;
  import java.util.Scanner;
  import java.util.StringTokenizer;
  
  public class Test{
  
          static FastReader scan;
  
          static void solve(){
              int n=scan.nextInt();
              int notes=scan.nextInt();
              notes++;
              int []arr=new int[n];
              for(int i=0;i<n;i++){
                  arr[i]=scan.nextInt();
              }
              
              long ans=0;
              for(int i=0;i<n-1;i++){
                  if(notes>0){
                      int currNotes=(int)Math.pow(10,arr[i+1]-arr[i]);
                      currNotes--;
  
                      currNotes=Math.min(notes,currNotes);
                      ans+=(long)(Math.pow(10,arr[i])*currNotes);
                      notes=notes-currNotes;
                  }  
                  else break;   
              }
              if(notes>0){
                  ans+=(long)(Math.pow(10,arr[n-1])*notes);
              }
  
              System.out.println(ans);       
  
  
  
          }
          
  
          public static void main (String[] args) throws java.lang.Exception{
              scan=new FastReader();
              int t=scan.nextInt();
              while(t-->0){
                  solve();
              }
          }
  
          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;
              }
          }
  
          static class Pair implements Comparable<Pair>{
              int e;
              int wt;
              Pair(int x,int y){
                  this.e=x;
                  this.wt=y;
              }
              @Override
              public int compareTo(Pair x){
                  return (int)(x.wt-this.wt);
              }
          }        
  
          static void printLong(long []arr){
              for(long x:arr)System.out.print(x+" ");
          }
  
          static void printInt(int []arr){
              for(int x:arr)System.out.print(x+" ");
          }
  
          static void scanInt(int []arr){
              for(int i=0;i<arr.length;i++){
                  arr[i]=scan.nextInt();
              }
          }
  
          static void scanLong(long []arr){
              for(int i=0;i<arr.length;i++){
                  arr[i]=scan.nextLong();
              }
          }
  
          static long gcd(long a, long b){
              if (b == 0)
                  return a;
              
              return gcd(b, a % b);
          }   
  
          static long power(long x, long y, long mod){
              long res = 1; 
          
              x = x % mod; 
           
              if (x == 0)
                return 0; 
           
              while (y > 0){              
                  if ((y & 1) != 0)
                  res = (res * x) % mod;
                
                  y = y >> 1; 
                  x = (x * x) % mod;
              }
                  return res;
          }
  
          static long add(long a,long b,long mod){
              a = a % mod; 
              b = b % mod; 
              return (((a + b) % mod) + mod) % mod;
          }
  
          static long sub(long a, long b,long mod){
              a = a % mod; 
              b = b % mod; 
              return (((a - b) % mod) + mod) % mod;
          }
  
          static long mul(long a, long b,long mod){
              a = a % mod; 
              b = b % mod; 
              return (((a * b) % mod) + mod) % mod;
          }
          
  
          static long mminvprime(long a, long b,long mod) {
              return power(a, b - 2,mod);
          }
  }
  