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.math.*;
  public class Main{
  	//見なくていいよ　ここから------------------------------------------
  	static class InputIterator{
  		ArrayList<String> inputLine = new ArrayList<>(buf);
  		int index = 0; int max; String read;
  		InputIterator(){
  			BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
  			try{
  				while((read = br.readLine()) != null){
  					inputLine.addAll(Arrays.asList(read.split(" ")));
  				}
  			}catch(IOException e){}
  			max = inputLine.size();
  		}
  		boolean hasNext(){return (index < max);}
  		String next(){
  			if(hasNext()){
  				return inputLine.get(index++);
  			}else{
  				throw new IndexOutOfBoundsException("There is no more input");
  			}
  		}
  	}
  	//入力バッファサイズのつもり。入力点数（スペース区切りでの要素数）が100万を超える場合はバッファサイズを100万にすること
  	static int buf = 1024;
  	static HashMap<Integer, String> CONVSTR = new HashMap<>();
  	static InputIterator ii = new InputIterator();//This class cannot be used in reactive problem.
  	static PrintWriter out = new PrintWriter(System.out);
  	static void flush(){out.flush();}
  	static void myout(Object t){out.println(t);}
  	static void myerr(Object t){System.err.print("debug:");System.err.println(t);}
  	static String next(){return ii.next();}
  	static boolean hasNext(){return ii.hasNext();}
  	static int nextInt(){return Integer.parseInt(next());}
  	static long nextLong(){return Long.parseLong(next());}
  	static double nextDouble(){return Double.parseDouble(next());}
  	static ArrayList<String> nextCharArray(){return myconv(next(), 0);}
  	static ArrayList<String> nextStrArray(int size){
  		ArrayList<String> ret = new ArrayList<>(size);
  		for(int i = 0; i < size; i++){
  			ret.add(next());
  		}
  		return ret;
  	}
  	static ArrayList<Integer> nextIntArray(int size){
  		ArrayList<Integer> ret = new ArrayList<>(size);
  		for(int i = 0; i < size; i++){
  			ret.add(Integer.parseInt(next()));
  		}
  		return ret;
  	}
  	static ArrayList<Long> nextLongArray(int size){
  		ArrayList<Long> ret = new ArrayList<>(size);
  		for(int i = 0; i < size; i++){
  			ret.add(Long.parseLong(next()));
  		}
  		return ret;
  	}
  	@SuppressWarnings("unchecked")
  	static String myconv(Object list, int no){//only join
  		StringBuilder sb = new StringBuilder("");
  		String joinString = CONVSTR.get(no);
  		if(list instanceof String[]){
  			return String.join(joinString, (String[])list);
  		}else if(list instanceof long[]){
  			long[] tmp = (long[])list;
  			if(tmp.length == 0){
  				return "";
  			}
  			sb.append(String.valueOf(tmp[0]));
  			for(int i = 1; i < tmp.length; i++){
  				sb.append(joinString).append(String.valueOf(tmp[i]));
  			}
  			return sb.toString();
  		}else if(list instanceof int[]){
  			int[] tmp = (int[])list;
  			if(tmp.length == 0){
  				return "";
  			}
  			sb.append(String.valueOf(tmp[0]));
  			for(int i = 1; i < tmp.length; i++){
  				sb.append(joinString).append(String.valueOf(tmp[i]));
  			}
  			return sb.toString();
  		}else if(list instanceof ArrayList){
  			ArrayList tmp = (ArrayList)list;
  			if(tmp.size() == 0){
  				return "";
  			}
  			sb.append(tmp.get(0));
  			for(int i = 1; i < tmp.size(); i++){
  				sb.append(joinString).append(tmp.get(i));
  			}
  			return sb.toString();
  		}else{
  			throw new ClassCastException("Don't join");
  		}
  	}
  	static ArrayList<String> myconv(String str, int no){//only split
  		String splitString = CONVSTR.get(no);
  		return new ArrayList<String>(Arrays.asList(str.split(splitString)));
  	}
  	static ArrayList<String> myconv(String str, String no){
  		return new ArrayList<String>(Arrays.asList(str.split(no)));
  	}
  	public static void main(String[] args){
  		CONVSTR.put(8, " "); CONVSTR.put(9, "\n"); CONVSTR.put(0, "");
  		solve();flush();
  	}
  	//見なくていいよ　ここまで------------------------------------------
  	//このコードをコンパイルするときは、「-encoding UTF-8」を指定すること
  	static void solve(){//ここがメイン関数
  		int t = nextInt();
  		while(hasNext()){
  			int N = nextInt();
  			long K = nextLong() + 1;
  			int[] list = new int[N];
  			for(int i = 0; i < N; i++){
  				list[i] = nextInt();
  			}
  			long output = 0;
  			for(int i = 0; i < N - 1; i++){
  				int useRange = list[i + 1] - list[i];
  				long diff = (long)Math.pow(10, useRange) - 1;
  				if(diff < K){
  					output += diff * (long)Math.pow(10, list[i]);
  					K -= diff;
  				}else{
  					output += K * (long)Math.pow(10, list[i]);
  					K = 0;
  					break;
  				}
  			}
  			output += K * (long)Math.pow(10, list[N - 1]);
  			myout(output);
  		}
  	}
  	//メソッド追加エリア　ここから
  
  
  
  	//メソッド追加エリア　ここまで
  }
  