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.BufferedReader;
  import java.io.IOException;
  import java.io.InputStreamReader;
  import java.io.PrintWriter;
  import java.util.*;
  
  public class Practice {
  	public static long mod = (long) Math.pow(10, 9) + 7;
  	public static long mod2 = 998244353;
  	public static int tt = 0;
  	public static ArrayList<Integer> prime;
  
  	public static void main(String[] args) throws Exception {
  		BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
  		PrintWriter pw = new PrintWriter(System.out);
  		int t = Integer.parseInt(br.readLine());
  		int p = 1;
  
  		// System.out.println(list.size());
  		while (t-- > 0) {
  			String[] s1 = br.readLine().split(" ");
  			int n = Integer.valueOf(s1[0]);
  			long k = Long.valueOf(s1[1]);
  			long[] arr = new long[n];
  			String str = (br.readLine());
  			String[] s2 = str.split(" ");
  			for (int i = 0; i < n; i++) {
  				arr[i] = Integer.parseInt(s2[i]);
  			}
  			long curr = 0;
  			String no = "";
  			for (int i = 1; i < n; i++) {
  				long c = (long) Math.pow(10, arr[i] - arr[i - 1]) - 1;
  				if (curr + c <= k + 1) {
  					curr += c;
  					for (int j = 0; j < arr[i] - arr[i - 1]; j++) {
  						no = '9' + no;
  					}
  				} else {
  					long pp = k + 1 - curr;
  					curr = k + 1;
  					if (pp == 0) {
  						break;
  					}
  					no = pp + no;
  					break;
  				}
  				// System.out.println(curr);
  			}
  			if (curr < k + 1) {
  				long need = k + 1 - curr;
  				no = need + no;
  			}
  			pw.println(no);
  
  		}
  		pw.close();
  	}
  
  }
  
  //	private static void getFac(long n, PrintWriter pw) {
  //		// TODO Auto-generated method stub
  //		int a = 0;
  //		while (n % 2 == 0) {
  //			a++;
  //			n = n / 2;
  //		}
  //		if (n == 1) {
  //			a--;
  //		}
  //		for (int i = 3; i <= Math.sqrt(n); i += 2) {
  //			while (n % i == 0) {
  //				n = n / i;
  //				a++;
  //			}
  //		}
  //		if (n > 1) {
  //			a++;
  //		}
  //		if (a % 2 == 0) {
  //			pw.println("Bob");
  //		} else {
  //			pw.println("Alice");
  //		}
  //		//System.out.println(a);
  //		return;
  //	}
  
  //	private static long power(long a, long p) {
  //		// TODO Auto-generated method stub
  //		long res = 1;
  //		while (p > 0) {
  //			if (p % 2 == 1) {
  //				res = (res * a) % mod;
  //			}
  //			p = p / 2;
  //			a = (a * a) % mod;
  //		}
  //		return res;
  //	}
  //
  //	private static void fac() {
  //		fac[0] = 1;
  //		// TODO Auto-generated method stub
  //		for (int i = 1; i < fac.length; i++) {
  //			if (i == 1) {
  //				fac[i] = 1;
  //			} else {
  //				fac[i] = i * fac[i - 1];
  //			}
  //			if (fac[i] > mod) {
  //				fac[i] = fac[i] % mod;
  //			}
  //		}
  //	}
  //
  //	private static int getLower(Long long1, Long[] st) {
  //		// TODO Auto-generated method stub
  //		int left = 0, right = st.length - 1;
  //		int ans = -1;
  //		while (left <= right) {
  //			int mid = (left + right) / 2;
  //			if (st[mid] <= long1) {
  //				ans = mid;
  //				left = mid + 1;
  //			} else {
  //				right = mid - 1;
  //			}
  //		}
  //		return ans;
  //	}
  
  //	private static long getGCD(long l, long m) {
  //
  //		long t1 = Math.min(l, m);
  //		long t2 = Math.max(l, m);
  //		while (true) {
  //			long temp = t2 % t1;
  //			if (temp == 0) {
  //				return t1;
  //			}
  //			t2 = t1;
  //			t1 = temp;
  //		}
  //	}