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: import java.io.*;
  import java.lang.reflect.Array;
  import java.math.BigInteger;
  import java.util.*;
  
  public class B {
      //--------------------------INPUT READER---------------------------------//
      static class fs {
          public BufferedReader br;
          StringTokenizer st = new StringTokenizer("");
  
          public fs() { this(System.in); }
          public fs(InputStream is) {
              br = new BufferedReader(new InputStreamReader(is));
          }
          String next() {
              while (!st.hasMoreTokens()) {
                  try { st = new StringTokenizer(br.readLine()); }
                  catch (IOException e) { e.printStackTrace(); }
              }
              return st.nextToken();
          }
  
          int ni() { return Integer.parseInt(next()); }
          long nl() { return Long.parseLong(next()); }
          double nd() { return Double.parseDouble(next()); }
          String ns() { return next(); }
  
          int[] na(long nn) {
              int n = (int) nn;
              int[] a = new int[n];
              for (int i = 0; i < n; i++) a[i] = ni();
              return a;
          }
  
          long[] nal(long nn) {
              int n = (int) nn;
              long[] l = new long[n];
              for(int i = 0; i < n; i++) l[i] = nl();
              return l;
          }
      }
      //-----------------------------------------------------------------------//
  
      //---------------------------PRINTER-------------------------------------//
      static class Printer {
          static PrintWriter w;
          public Printer() {this(System.out);}
          public Printer(OutputStream os) {
              w = new PrintWriter(os);
          }
          public void p(int i) {w.println(i);}
          public void p(long l) {w.println(l);}
          public void p(double d) {w.println(d);}
          public void p(String s) { w.println(s);}
          public void pr(int i) {w.print(i);}
          public void pr(long l) {w.print(l);}
          public void pr(double d) {w.print(d);}
          public void pr(String s) { w.print(s);}
          public void pl() {w.println();}
          public void close() {w.close();}
      }
      //-----------------------------------------------------------------------//
  
      //--------------------------VARIABLES------------------------------------//
      static fs sc = new fs();
      static OutputStream outputStream = System.out;
      static Printer w = new Printer(outputStream);
      static long lma = Long.MAX_VALUE, lmi = Long.MIN_VALUE;
      static int ima = Integer.MAX_VALUE, imi = Integer.MIN_VALUE;
      static long mod = 1000000007;
      //-----------------------------------------------------------------------//
  
      //--------------------------ADMIN_MODE-----------------------------------//
      private static void ADMIN_MODE() throws IOException {
          if (System.getProperty("ONLINE_JUDGE") == null) {
              w = new Printer(new FileOutputStream("output.txt"));
              sc = new fs(new FileInputStream("input.txt"));
          }
      }
      //-----------------------------------------------------------------------//
  
      //----------------------------START--------------------------------------//
      public static void main(String[] args)
              throws IOException {
  
          ADMIN_MODE();
  
          int t = sc.ni();while(t-->0)
              solve();
  
  
          w.close();
      }
  
      static void solve() throws IOException {
          int n = sc.ni(), k = sc.ni();
          x = sc.nl();
          String str = sc.ns();
          char[] strr = str.toCharArray();
          List<Integer> intervals  = intervals(str, k);
          res = new int[intervals.size()];
  
          if(x == 1) {
              StringBuilder sb = new StringBuilder();
              for(int i = 0; i < n; i++) {
                  if(strr[i]!='*') sb.append('a');
              }
              w.p(sb.toString());
              return;
          }
  
          while(x > 0) {
              res(intervals);
          }
  
          ArrayDeque<Character> q = new ArrayDeque<>();
  
          int id = 0;
  
          boolean f = false;
          for(int i = n-1; i >= 0; i--) {
              if(strr[i]=='a') {
                  q.addFirst('a');
                  f = false;
              }
              else if(!f) {
                  for(int j = 0; j < res[id]; j++) {
                      q.addFirst('b');
                  }
                  id++;
                  f = true;
              }
          }
  
          for(char i: q) {
              w.pr(i+"");
          }
          w.pl();
      }
  
      static long x;
      static int[] res;
  
      static void res(List<Integer> intervals) {
          BigInteger rank = BigInteger.valueOf(1);
          BigInteger x = BigInteger.valueOf(B.x);
          for(int i = 0; i < intervals.size(); i++) {
              int curr = intervals.get(i);
              if(BigInteger.valueOf(curr).multiply(rank).compareTo(x) < 0) {
                  rank = rank.multiply(BigInteger.valueOf(curr));
              } else {
                  if(i == 0) {
                      res[i] = (x.subtract(BigInteger.valueOf(1))).intValue();
                      B.x = 0;
                  } else {
                      BigInteger extra = x.subtract(rank);
                      BigInteger needed = (extra.divide(rank));
                      if (extra.mod(rank).intValue() == 0) {
                          res[i] = needed.intValue();
                      } else {
                          res[i] = needed.intValue() + 1;
                      }
                      B.x -= rank.longValue() * res[i];
                  }
                  return;
              }
          }
      }
  
      static List<Integer> intervals (String str, int k) {
          char[] strr = str.toCharArray();
          int n = strr.length;
          int ct = 0;
          List<Integer> res = new ArrayList<>();
          for(int i = n-1; i >= 0; i--) {
              if(strr[i]=='*') ct++;
              else if(ct != 0) {
                  res.add(ct*k+1);
                  ct = 0;
              }
          }
          if(ct != 0) res.add(ct*k+1);
          return res;
      }
  
  }