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: // हर हर महादेव
  import java.util.*;
  import java.lang.*;
  import java.io.*;
  import java.text.DecimalFormat;
  
  public final class Solution {
  
      static int inf = Integer.MAX_VALUE;
      static long mod = 1000000000 + 7;
     
      
  
    
   static void ne(Reader sc, BufferedWriter op) throws Exception {
       int n= sc.nextInt();
       long k=sc.nextLong();
       long[] arr= new long[n];
       for(int i=0;i<n;i++){
         arr[i]=sc.nextLong();
       }
       long curr=0;
       boolean ff=false;
      //  long notes=0;
       for(int i=0;i<n-1;i++){
         
          long diff=(no(arr[i+1])/no(arr[i]))-1;
          
          if(diff>k){
      
             k++;
             curr+=k*no(arr[i]);
             k=0;
             
             break;
          }else{
              curr+=diff*no(arr[i]);
              k-=diff;
              if(k==0){
                  curr+=no(arr[i+1]);
                  break;
              }
          }
       }
       if(k>0){
           k++;
           curr+=k*no(arr[n-1]);
       }
       op.write(curr+"\n");
      
  
      
  
   }
    static long no(long num){
        long ans=1L;
      while(num-->0){
          ans*=10L;
      }
      return ans;
    }
  
       
  
  
  
    
  
      static long gcd(long a, long b){
          if(a==0) return b;
          return gcd(b%a,a);
      }
      // static int lcm(int a, int b){
      //     return (a*b)/gcd(a,b);
      // }
  
      public static void main(String[] args) throws Exception {
          BufferedWriter op = new BufferedWriter(new OutputStreamWriter(System.out));
          // Reader sc = new Reader();
          Reader sc= new Reader();
          int t = sc.nextInt();
          while (t-->0){ne(sc, op);}
          
          // ne(sc,op);
             
                     
          op.flush();
      }
  
      static void print(Object o) {
          System.out.println(String.valueOf(o));
      }
      static int[] toIntArr(String s){
          int[] val= new int[s.length()];
          for(int i=0;i<s.length();i++){
              val[i]=s.charAt(i)-'a';
          }
          return val;
      }
      static void  sort(int[] arr){
          ArrayList<Integer> list= new ArrayList<>();
          for(int i=0;i<arr.length;i++){
              list.add(arr[i]);
  
          }
          Collections.sort(list);
          for(int i=0;i<arr.length;i++){
              arr[i]=list.get(i);
          }
      }
         static void  sort(long[] arr){
          ArrayList<Long> list= new ArrayList<>();
          for(int i=0;i<arr.length;i++){
              list.add(arr[i]);
  
          }
          Collections.sort(list);
          for(int i=0;i<arr.length;i++){
              arr[i]=list.get(i);
          }
      }
  
  }
  
  // return -1 to put no ahed in array
  class pair {
      int xx;
  
      int yy;
  
  
      pair(int xx, int yy ) {
          this.xx = xx;
          this.yy = yy;
      }
  }
  
  
  class sortY implements Comparator<pair> {
      public int compare(pair p1, pair p2) {
          if (p1.yy > p2.yy) {
              return -1;
          } else if (p1.yy == p2.yy) {
              if (p1.xx > p2.xx) {
                  return 1;
              } else if (p1.xx < p2.xx) {
                  return -1;
              }
              return 0;
  
          }
          return 1;
      }
  }
  
  class sortX implements Comparator<pair> {
      public int compare(pair p1, pair p2) {
          if (p1.xx > p2.xx) {
              return 1;
          } else if (p1.xx == p2.xx) {
              if (p1.yy > p2.yy) {
                  return 1;
              } else if (p1.yy < p2.yy) {
                  return -1;
              }
              return 0;
  
          }
          return -1;
      }
  }
  
  class debug {
  
      static void print1d(long[] arr) {
          System.out.println();
          for (int i = 0; i < arr.length; i++) {
              System.out.print(arr[i] + " ");
          }
  
      }
  
      static void print1d(int[] arr) {
          System.out.println();
          for (int i = 0; i < arr.length; i++) {
              System.out.print(arr[i] + " ");
          }
  
      }
  
      static void print1d(boolean[] arr) {
          System.out.println();
          for (int i = 0; i < arr.length; i++) {
              System.out.println(i + "= " + arr[i] + " ");
          }
  
      }
  
      static void print2d(int[][] arr) {
          System.out.println();
          int n = arr.length;
          int n2 = arr[0].length;
          for (int i = 0; i < n; i++) {
              for (int j = 0; j < n2; j++) {
                  System.out.print(arr[i][j] + " ");
              }
              System.out.println();
          }
  
      }
  
      static void print2d(long[][] arr) {
          System.out.println();
          int n = arr.length;
          int n2 = arr[0].length;
          for (int i = 0; i < n; i++) {
              for (int j = 0; j < n2; j++) {
                  System.out.print(arr[i][j] + " ");
              }
              System.out.println();
          }
  
      }
       static void printPair(ArrayList<pair> list) {
          if(list.size()==0){
              System.out.println("empty list");
              return;
          }
         System.out.println();
         for(int i=0;i<list.size();i++){
            System.out.println(list.get(i).xx+"-"+list.get(i).yy);
         }
      }
  
  }
  
  class Reader {
      final private int BUFFER_SIZE = 1 << 16;
      private DataInputStream din;
      private byte[] buffer;
      private int bufferPointer, bytesRead;
  
      public Reader() {
          din = new DataInputStream(System.in);
          buffer = new byte[BUFFER_SIZE];
          bufferPointer = bytesRead = 0;
      }
  
      public Reader(String file_name) throws IOException {
          din = new DataInputStream(new FileInputStream(file_name));
          buffer = new byte[BUFFER_SIZE];
          bufferPointer = bytesRead = 0;
      }
  
      public String readLine() throws IOException {
          byte[] buf = new byte[64]; // line length
          int cnt = 0, c;
          while ((c = read()) != -1) {
              if (c == '\n') {
                  if (cnt != 0) {
                      break;
                  } else {
                      continue;
                  }
              }
              buf[cnt++] = (byte) c;
          }
          return new String(buf, 0, cnt);
      }
  
      public int nextInt() throws IOException {
          int ret = 0;
          byte c = read();
          while (c <= ' ') {
              c = read();
          }
          boolean neg = (c == '-');
          if (neg)
              c = read();
          do {
              ret = ret * 10 + c - '0';
          } while ((c = read()) >= '0' && c <= '9');
  
          if (neg)
              return -ret;
          return ret;
      }
  
      public long nextLong() throws IOException {
          long ret = 0;
          byte c = read();
          while (c <= ' ')
              c = read();
          boolean neg = (c == '-');
          if (neg)
              c = read();
          do {
              ret = ret * 10 + c - '0';
          } while ((c = read()) >= '0' && c <= '9');
          if (neg)
              return -ret;
          return ret;
      }
  
      public double nextDouble() throws IOException {
          double ret = 0, div = 1;
          byte c = read();
          while (c <= ' ')
              c = read();
          boolean neg = (c == '-');
          if (neg)
              c = read();
  
          do {
              ret = ret * 10 + c - '0';
          } while ((c = read()) >= '0' && c <= '9');
  
          if (c == '.') {
              while ((c = read()) >= '0' && c <= '9') {
                  ret += (c - '0') / (div *= 10);
              }
          }
  
          if (neg)
              return -ret;
          return ret;
      }
  
      private void fillBuffer() throws IOException {
          bytesRead = din.read(buffer, bufferPointer = 0, BUFFER_SIZE);
          if (bytesRead == -1)
              buffer[0] = -1;
      }
  
      private byte read() throws IOException {
          if (bufferPointer == bytesRead)
              fillBuffer();
          return buffer[bufferPointer++];
      }
  
      public void close() throws IOException {
          if (din == null)
              return;
          din.close();
      }
  }
    class MultiTreeSet<E> {
  	TreeMap<E, Integer> freqTreeMap = new TreeMap<E, Integer>();
  	int size;
   
  	public MultiTreeSet() {}
   
  	public MultiTreeSet(Collection<? extends E> c) {
  		for(E element : c)
  			add(element);
  	}
   
  	public int size() {
  		return size;
  	}
      public int disCount(){
          return freqTreeMap.size();
      }
   
  	public void add(E element) {
  		Integer freq = freqTreeMap.get(element);
  		if(freq==null)
  			freqTreeMap.put(element, 1);
  		else
  			freqTreeMap.put(element,freq+1);
  		++size;
  	}
   
  	public void remove(E element) {
  		Integer freq = freqTreeMap.get(element);
  		if(freq!=null) {
  			if(freq==1)
  				freqTreeMap.remove(element);
  			else
  				freqTreeMap.put(element, freq-1);
  			--size;
  		}
  	}
  
   
  	public int get(E element) {
  		Integer freq = freqTreeMap.get(element);
  		if(freq==null)
  			return 0;
  		return freq;
  	}
   
  	public boolean contains(E element) {
  		return get(element)>0;
  	}
      public void print(){
          for(E k : freqTreeMap.keySet()){
              System.out.print(k+"="+freqTreeMap.get(k)+" ");
          }
          System.out.println();
      }
   
  	public boolean isEmpty() {
  		return size==0;
  	}
   
  	public E first() {
  		return freqTreeMap.firstKey();
  	}
   
  	public E last() {
  		return freqTreeMap.lastKey();
  	}
   
  	public E ceiling(E element) {
  		return freqTreeMap.ceilingKey(element);
  	}
   
  	public E floor(E element) {
  		return freqTreeMap.floorKey(element);
  	}
   
  	public E higher(E element) {
  		return freqTreeMap.higherKey(element);
  	}
   
  	public E lower(E element) {
  		return freqTreeMap.lowerKey(element);
  	}
  }
   