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 {
    static StringBuilder sb;
    static long fact[];
    static int mod = (int) (1e9 + 7);
  
    static class Pair implements Comparable<Pair> {
      int u;
      int v;
      int w;
  
      Pair(int u, int v) {
        this.u = u;
        this.v = v;
      }
  
      public int compareTo(Pair o) {
        return (int) (this.v - o.v);
      }
    }
    
  
    static void solve() {
        int n= i();
        int k = i();
        
        int[] arr = readArray(n);
        for(int i=0; i < n; i++){
            arr[i] = (int)Math.pow(10,arr[i]);
        }
        
        long ans = 0;
        long temp = 0;
        int tidx = -1;
        for(int i =0 ; i < n-1; i++){
            temp += arr[i+1]/arr[i] - 1;
            if(temp > k){
                temp -= arr[i+1]/arr[i] - 1;
                tidx = i;
                break;
            }
            ans += arr[i+1] - arr[i];
        }
        
        //System.out.println(temp + " " + tidx);
        if(tidx == -1){
            temp = k+1 - temp;
            ans += arr[n-1]*temp;
        }else{
          temp = k+1 - temp;
          ans += arr[tidx]*temp;
        }
       
        sb.append(ans);
    }
   
   
    public static void main(String[] args) {
      sb = new StringBuilder();
      
      fact = new long[(int)1e6+10];
      fact[0] = fact[1]=1;
      for(int i=2;i<fact.length;i++){
          fact[i] = ((long)(i%mod)*1L*(long)(fact[i-1]%mod))%mod;
      }
      
      int test = i();
      while (test-- > 0) {
        solve();
        sb.append("\n");
      }
      System.out.print(sb);
    }
    
    
    static long ncr(int n, int r) {
      if (r > n)
        return (long) 0;
  
      long res = fact[n] % mod;
      // System.out.println(res);
      res = ((long) (res % mod) * (long) (p(fact[r], mod - 2) % mod)) % mod;
      res = ((long) (res % mod) * (long) (p(fact[n - r], mod - 2) % mod)) % mod;
      // System.out.println(res);
      return res;
  
    }
    
    // **************NCR%P******************
  
    static long p(long x, long y)// POWER FXN //
    {
      if (y == 0)
        return 1;
  
      long res = 1;
      while (y > 0) {
        if (y % 2 == 1) {
          res = (res * x) % mod;
          y--;
        }
  
        x = (x * x) % mod;
        y = y / 2;
  
      }
      return res;
    }
  
    // **************END******************
  
    // *************Disjoint set
    // union*********//
  
    // ***************PRIME FACTORIZE
    // ***********************************//
    static TreeMap<Integer, Integer> prime(long n) {
      TreeMap<Integer, Integer> h = new TreeMap<>();
      long num = n;
      for (int i = 2; i <= Math.sqrt(num); i++) {
        if (n % i == 0) {
          int nt = 0;
          while (n % i == 0) {
            n = n / i;
            nt++;
          }
          h.put(i, nt);
        }
      }
      if (n != 1)
        h.put((int) n, 1);
      return h;
  
    }
  
    // *****CLASS PAIR
    // *************************************************
  
    // *****CLASS PAIR
    // ***************************************************
  
    static class InputReader {
      private InputStream stream;
      private byte[] buf = new byte[1024];
      private int curChar;
      private int numChars;
      private SpaceCharFilter filter;
  
      public InputReader(InputStream stream) {
        this.stream = stream;
      }
  
      public int read() {
        if (numChars == -1)
          throw new InputMismatchException();
        if (curChar >= numChars) {
          curChar = 0;
          try {
            numChars = stream.read(buf);
          } catch (IOException e) {
            throw new InputMismatchException();
          }
          if (numChars <= 0)
            return -1;
        }
        return buf[curChar++];
      }
  
      public int Int() {
        int c = read();
        while (isSpaceChar(c))
          c = read();
        int sgn = 1;
        if (c == '-') {
          sgn = -1;
          c = read();
        }
        int res = 0;
        do {
          if (c < '0' || c > '9')
            throw new InputMismatchException();
          res *= 10;
          res += c - '0';
          c = read();
        } while (!isSpaceChar(c));
        return res * sgn;
      }
  
      public String String() {
        int c = read();
        while (isSpaceChar(c))
          c = read();
        StringBuilder res = new StringBuilder();
        do {
          res.appendCodePoint(c);
          c = read();
        } while (!isSpaceChar(c));
        return res.toString();
      }
  
      public boolean isSpaceChar(int c) {
        if (filter != null)
          return filter.isSpaceChar(c);
        return c == ' ' || c == '\n' || c == '\r' || c == '\t' || c == -1;
      }
  
      public String next() {
        return String();
      }
  
      public interface SpaceCharFilter {
        public boolean isSpaceChar(int ch);
      }
    }
  
    static class OutputWriter {
      private final PrintWriter writer;
  
      public OutputWriter(OutputStream outputStream) {
        writer = new PrintWriter(new BufferedWriter(new OutputStreamWriter(outputStream)));
      }
  
      public OutputWriter(Writer writer) {
        this.writer = new PrintWriter(writer);
      }
  
      public void print(Object... objects) {
        for (int i = 0; i < objects.length; i++) {
          if (i != 0)
            writer.print(' ');
          writer.print(objects[i]);
        }
      }
  
      public void printLine(Object... objects) {
        print(objects);
        writer.println();
      }
  
      public void close() {
        writer.close();
      }
  
      public void flush() {
        writer.flush();
      }
    }
  
    static InputReader in = new InputReader(System.in);
    static OutputWriter out = new OutputWriter(System.out);
  
    public static long[] sort(long[] a2) {
      int n = a2.length;
      ArrayList<Long> l = new ArrayList<>();
      for (long i : a2)
        l.add(i);
      Collections.sort(l);
      for (int i = 0; i < l.size(); i++)
        a2[i] = l.get(i);
      return a2;
    }
  
    public static long pow(long x, long y) {
      long res = 1;
      while (y > 0) {
        if (y % 2 != 0) {
          res = (res * x);// % modulus;
          y--;
  
        }
        x = (x * x);// % modulus;
        y = y / 2;
      }
      return res;
    }
  
    // GCD___+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
    public static long gcd(long x, long y) {
      if (x == 0)
        return y;
      else
        return gcd(y % x, x);
    }
    // ******LOWEST COMMON MULTIPLE
    // *********************************************
  
    public static long lcm(long x, long y) {
      return (x * (y / gcd(x, y)));
    }
  
    // INPUT
    // PATTERN********************************************************
    public static int i() {
      return in.Int();
    }
  
    public static long l() {
      String s = in.String();
      return Long.parseLong(s);
    }
  
    public static String s() {
      return in.String();
    }
  
    public static int[] readArray(int n) {
      int A[] = new int[n];
      for (int i = 0; i < n; i++) {
        A[i] = i();
      }
      return A;
    }
  
    public static long[] readArray(long n) {
      long A[] = new long[(int) n];
      for (int i = 0; i < n; i++) {
        A[i] = l();
      }
      return A;
    }
  
  }