description: You are given an integer k and a string s that consists only of characters 'a' (a lowercase Latin letter) and '*' (an asterisk).
  
  Each asterisk should be replaced with several (from 0 to k inclusive) lowercase Latin letters 'b'. Different asterisk can be replaced with different counts of letter 'b'.
  
  The result of the replacement is called a BA-string.
  
  Two strings a and b are different if they either have different lengths or there exists such a position i that a_i ≠ b_i.
  
  A string a is lexicographically smaller than a string b if and only if one of the following holds: 
  
    * a is a prefix of b, but a ≠ b; 
    * in the first position where a and b differ, the string a has a letter that appears earlier in the alphabet than the corresponding letter in b. 
  
  
  
  Now consider all different BA-strings and find the x-th lexicographically smallest of them.
  
  Input
  
  The first line contains a single integer t (1 ≤ t ≤ 2000) — the number of testcases.
  
  The first line of each testcase contains three integers n, k and x (1 ≤ n ≤ 2000; 0 ≤ k ≤ 2000; 1 ≤ x ≤ 10^{18}). n is the length of string s.
  
  The second line of each testcase is a string s. It consists of n characters, each of them is either 'a' (a lowercase Latin letter) or '*' (an asterisk).
  
  The sum of n over all testcases doesn't exceed 2000. For each testcase x doesn't exceed the total number of different BA-strings. String s contains at least one character 'a'.
  
  Output
  
  For each testcase, print a single string, consisting only of characters 'b' and 'a' (lowercase Latin letters) — the x-th lexicographically smallest BA-string.
  
  Example
  
  Input
  
  
  3
  2 4 3
  a*
  4 1 3
  a**a
  6 3 20
  **a***
  
  
  Output
  
  
  abb
  abba
  babbbbbbbbb
  
  Note
  
  In the first testcase of the example, BA-strings ordered lexicographically are: 
  
    1. a
    2. ab
    3. abb
    4. abbb
    5. abbbb
  
  
  
  In the second testcase of the example, BA-strings ordered lexicographically are: 
  
    1. aa
    2. aba
    3. abba
  
  
  
  Note that string "aba" is only counted once, even though there are two ways to replace asterisks with characters 'b' to get it.
solution: /*
          "Everything in the universe is balanced. Every disappointment
                  you face in life will be balanced by something good for you!
                          Keep going, never give up."
  
  */
  
  
  
  import java.util.*;
  import java.lang.*;
  import java.io.*;
  
  public class Solution {
      public static void main(String[] args) throws java.lang.Exception {
          out = new PrintWriter(new BufferedOutputStream(System.out));
          sc = new FastReader();
  
          int test = sc.nextInt();
          for (int t = 0; t < test; t++) {
              solve();
          }
          out.close();
      }
  
      private static void solve() {
          int n = sc.nextInt();
          int k = sc.nextInt();
          long x = sc.nextLong();
  
          char[] arr = sc.next().toCharArray();
  
          x--; // don't replace any asterisk with b
  
          List<Integer> asteriskSizes = new ArrayList<>(); // total b's we can get from an asterisk segment + 1 (replacing * with empty string)
  
          StringBuilder curr = new StringBuilder();
          int count = 0;
          for (int i = 0; i < n; i++) {
              if (arr[i] == '*') {
                  count++;
              }else if (count > 0) {
                  asteriskSizes.add(k * count + 1);
                  count = 0;
              }
  
              if (i > 0 && (arr[i] != arr[i - 1] || arr[i - 1] == 'a')) { // used to build the resultant string
                  curr.append(arr[i - 1]);
              }
          }
  
          if (count > 0) {
              asteriskSizes.add(k * count + 1);
          }
  
          curr.append(arr[n - 1]);
  
          int m = asteriskSizes.size();
          long[] total = new long[m]; // total b's we should replace * with at ith asterisk segment, to get the xth lexicographically AB-string
          for (int i = m - 1; i >= 0; i--) {
              long place = x % asteriskSizes.get(i);
  
              total[i] = place;
              x /= asteriskSizes.get(i);
          }
  
          StringBuilder res = new StringBuilder();
          int index = 0;
  
          // build the smallest distinct xth lexicographically AB-string
          for (int i = 0; i < curr.length(); i++) {
              if (curr.charAt(i) == 'a') {
                  res.append('a');
              }else {
                  for (int j = 0; j < total[index]; j++) {
                      res.append('b');
                  }
                  index++;
              }
          }
          out.println(res);
      }
  
  
      public static FastReader sc;
      public static PrintWriter out;
      static class FastReader
      {
          BufferedReader br;
          StringTokenizer str;
  
          public FastReader()
          {
              br = new BufferedReader(new
                      InputStreamReader(System.in));
          }
  
          String next()
          {
              while (str == null || !str.hasMoreElements())
              {
                  try
                  {
                      str = new StringTokenizer(br.readLine());
                  }
                  catch (IOException  end)
                  {
                      end.printStackTrace();
                  }
              }
              return str.nextToken();
          }
  
          int nextInt()
          {
              return Integer.parseInt(next());
          }
  
          long nextLong()
          {
              return Long.parseLong(next());
          }
  
          double nextDouble()
          {
              return Double.parseDouble(next());
          }
  
          String nextLine()
          {
              String str = "";
              try
              {
                  str = br.readLine();
              }
              catch (IOException end)
              {
                  end.printStackTrace();
              }
              return str;
          }
      }
  }