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: //package codeforces;
  import java.io.BufferedReader;
  import java.io.IOException;
  import java.io.InputStreamReader;
  import java.io.PrintWriter;
  import java.util.*;
  public class solution{ 
  	public static void main(String[] args){
  		Scanner s=new Scanner(System.in);
      	PrintWriter out=new PrintWriter(System.out);
      	int t=s.nextInt();
      	for(int tt=0;tt<t;tt++) {
      		int n=s.nextInt(),k=s.nextInt()+1;
      		int a[]=new int[n];
      		for(int i=0;i<n;i++) {
      			a[i]=s.nextInt();
      		}
      		long ans=0;
      		for(int i=0;i<n && k!=0;i++) {
      			if(i==n-1) {
      				ans+=(long)Math.pow(10, a[i])*k;
      			}else {
      				long d=(long)Math.pow(10,a[i+1]-a[i])-1;
      				long temp=(long)Math.pow(10, a[i]);
      				if(k>d) {
      					ans+=temp*d;
      					k-=d;
      				}else {
      					ans+=temp*k;
      					k=0;
      				}
      			}
      		}
      		out.println(ans);
      	}
      	s.close();
      	out.close();
      }
  	public static void printb(boolean ans) {
  		if(ans) {
  			System.out.println("Yes");
  		}else {
  			System.out.println("No");
  		}
  	}
  	static boolean isPrime(int n){
          if (n <= 1)
              return false;
          else if (n == 2)
              return true;
          else if (n % 2 == 0)
              return false;
          for (int i = 3; i <= Math.sqrt(n); i += 2){
              if (n % i == 0)
                  return false;
          }
          return true;
      }
  	static long lcm(long a, long b){
  	      return (a*b)/(gcd(a,b));
  	    }
  	static long gcd(long a, long b){
  	      if (b == 0)
  	        return a;
  	      return gcd(b, a % b);
  	    }
      static void sort(long [] a) {
  		ArrayList<Long> l=new ArrayList<>();
  		for (long i:a) l.add(i);
  		Collections.sort(l);
  		for (int i=0; i<a.length; i++) a[i]=l.get(i);
  	}
      static void sort(int [] a) {
  		ArrayList<Integer> l=new ArrayList<>();
  		for (int i:a) l.add(i);
  		Collections.sort(l);
  		for (int i=0; i<a.length; i++) a[i]=l.get(i);
  	}
      static class FastScanner {
  		BufferedReader br=new BufferedReader(new InputStreamReader(System.in));
  		StringTokenizer st=new StringTokenizer("");
  		String next() {
  			while (!st.hasMoreTokens())
  				try {
  					st=new StringTokenizer(br.readLine());
  				} catch (IOException e) {
  					e.printStackTrace();
  				}
  			return st.nextToken();
  		}
  		double nextDouble() {
  			return Double.parseDouble(next());
  		}
  		int nextInt() {
  			return Integer.parseInt(next());
  		}
  		boolean nextBoolean() {
  			return Boolean.parseBoolean(next());
  		}
  		int[] readArray(int n) {
  			int[] a=new int[n];
  			for (int i=0; i<n; i++) a[i]=nextInt();
  			return a;
  		}
  		long nextLong() {
  			return Long.parseLong(next());
  		}
  		long[] readLongArray(int n) {
  			long[] a=new long[n];
  			for (int i=0; i<n; i++) a[i]=nextLong();
  			return a;
  		}
  	}
      static class Pair implements Comparable<Pair>{
      	int a,b ; 
      	Pair(int a,int b){
      		this.a=a;
      		this.b=b;
      	}
      	public int compareTo(Pair o) {
      		return a-o.a;
      	}
      }
  }
  