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.math.*;
  import java.util.*;
  
  
  // @author : Dinosparton 
  
  public class test {
  	 
  	   static class Pair{ 
  		   long x;
  		   long y;
  		   
  		   Pair(long x,long y){ 
  			   this.x = x;
  			   this.y = y;
  			   
  		   }
  	   }
  	 
  	   static class Sort implements Comparator<Pair>
  	   {
  
  	       @Override
  	       public int compare(Pair a, Pair b)
  	       {
  	           if(a.x!=b.x)
  	           {
  	               return (int)(a.x - b.x);
  	           }
  	           else
  	           {
  	               return (int)(a.y-b.y);
  	           }
  	       }
  	   }
  	   
  	   static class Compare { 
  		   
  		     void compare(Pair arr[], int n) 
  		    { 
  		        // Comparator to sort the pair according to second element 
  		        Arrays.sort(arr, new Comparator<Pair>() { 
  		            @Override public int compare(Pair p1, Pair p2) 
  		            { 
  		            	if(p1.x!=p2.x) {
  		                return (int)(p1.x - p2.x); 
  		            	}
  		            	else { 
  		            		return (int)(p1.y - p2.y);
  		            	}
  		            } 
  		        }); 
  		  
  //		        for (int i = 0; i < n; i++) { 
  //		            System.out.print(arr[i].x + " " + arr[i].y + " "); 
  //		        } 
  //		        System.out.println(); 
  		    } 
  		} 
  	 
  	   static class Scanner {
  	        BufferedReader br;
  	        StringTokenizer st;
  	 
  	        public Scanner()
  	        {
  	            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;
  	        }
  	    }
  	   
  	 
  	   public static void main(String args[]) throws Exception { 
  		
  		   
  		   Scanner sc = new Scanner();
  		   StringBuilder res = new StringBuilder();
  		
  		   int tc = sc.nextInt();
  		  
  		   while(tc-->0) { 
  			
  			int n = sc.nextInt();
  			long k = sc.nextLong()+1;
  			
  			int a[] = new int[n];
  			
  			for(int i=0;i<n;i++) {
  				a[i] = sc.nextInt();
  			}
  			
  			long cnt = 0;
  			
  			for(int i=0;i<n-1;i++) {
  				if(k>0) {
  					
  					long temp = (long)Math.pow(10, a[i+1]-a[i])-1;
  					long val = Math.min(temp, k);
  					k-= val;
  					cnt += Math.pow(10, a[i])*val;
  				}
  				else {
  					break;
  				}
  			}
  			if(k>0)
  			  cnt += (long)Math.pow(10, a[n-1])*k;
  			res.append(cnt+"\n");
  		   }
  		   System.out.println(res);
  	   }
  }  
  
  
  
  
  