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 sys
  read=sys.stdin.buffer.read;readline=sys.stdin.buffer.readline;input=lambda:sys.stdin.readline().rstrip()
  import bisect,string,math,time,functools,random,fractions
  from bisect import*
  from heapq import heappush,heappop,heapify
  from collections import deque,defaultdict,Counter
  from itertools import permutations,combinations,groupby
  rep=range;R=range
  def I():return int(input())
  def LI():return [int(i) for i in input().split()]
  def SLI():return sorted([int(i) for i in input().split()])
  def LI_():return [int(i)-1 for i in input().split()]
  def S_():return input()
  def IS():return input().split()
  def LS():return [i for i in input().split()]
  def NI(n):return [int(input()) for i in range(n)]
  def NI_(n):return [int(input())-1 for i in range(n)]
  def NLI(n):return [[int(i) for i in input().split()] for i in range(n)]
  def NLI_(n):return [[int(i)-1 for i in input().split()] for i in range(n)]
  def StoLI():return [ord(i)-97 for i in input()]
  def ItoS(n):return chr(n+97)
  def LtoS(ls):return ''.join([chr(i+97) for i in ls])
  def RLI(n=8,a=1,b=10):return [random.randint(a,b)for i in range(n)]
  def RI(a=1,b=10):return random.randint(a,b)
  def INP():
      N=10
      n=random.randint(2,N)
      mn=1
      mx=5
      a=[random.randint(mn,mx) for i in range(n)]
      s=[random.randint(mn,mx) for i in range(n)]
      return (n,a,s)
  def Rtest(T):
      case,err=0,0
      for i in range(T):
          inp=INP()
          a1=naive(*inp)
          a2=solve(*inp)
          if a1!=a2:
              x,y=a1
              z,w=a2
              cm=Comb(max(x,z))
              if cm.comb(x,y)==cm.comb(z,w):
                  case+=1
                  continue
              print(inp)
              print('naive',a1)
              print('solve',a2)
              err+=1
          case+=1
      print('Tested',case,'case with',err,'errors')
  def GI(V,E,ls=None,Directed=False,index=1):
      org_inp=[];g=[[] for i in range(V)]
      FromStdin=True if ls==None else False
      for i in range(E):
          if FromStdin:
              inp=LI()
              org_inp.append(inp)
          else:
              inp=ls[i]
          if len(inp)==2:a,b=inp;c=1
          else:a,b,c=inp
          if index==1:a-=1;b-=1
          aa=(a,c);bb=(b,c);g[a].append(bb)
          if not Directed:g[b].append(aa)
      return g,org_inp
  def RE(E):
      rt=[[]for i in range(len(E))]
      for i in range(len(E)):
          for nb,d in E[i]:
              rt[nb]+=(i,d),
      return rt
  def GGI(h,w,search=None,replacement_of_found='.',mp_def={'#':1,'.':0},boundary=1):
      #h,w,g,sg=GGI(h,w,search=['S','G'],replacement_of_found='.',mp_def={'#':1,'.':0},boundary=1) # sample usage
      mp=[boundary]*(w+2);found={}
      for i in R(h):
          s=input()
          for char in search:
              if char in s:
                  found[char]=((i+1)*(w+2)+s.index(char)+1)
                  mp_def[char]=mp_def[replacement_of_found]
          mp+=[boundary]+[mp_def[j] for j in s]+[boundary]
      mp+=[boundary]*(w+2)
      return h+2,w+2,mp,found
  def TI(n):return GI(n,n-1)
  def accum(ls):
      rt=[0]
      for i in ls:rt+=[rt[-1]+i]
      return rt
  def bit_combination(n,base=2):
      rt=[]
      for tb in R(base**n):s=[tb//(base**bt)%base for bt in R(n)];rt+=[s]
      return rt
  def gcd(x,y):
      if y==0:return x
      if x%y==0:return y
      while x%y!=0:x,y=y,x%y
      return y
  def YN(x):print(['NO','YES'][x])
  def Yn(x):print(['No','Yes'][x])
  def show(*inp,end='\n'):
      if show_flg:print(*inp,end=end)
  
  mo=10**9+7
  mo=998244353
  inf=float('inf')
  FourNb=[(-1,0),(1,0),(0,1),(0,-1)];EightNb=[(-1,0),(1,0),(0,1),(0,-1),(1,1),(-1,-1),(1,-1),(-1,1)];compas=dict(zip('WENS',FourNb));cursol=dict(zip('LRUD',FourNb))
  alp=[chr(ord('a')+i)for i in range(26)]
  #sys.setrecursionlimit(10**7)
  
  
  show_flg=False
  show_flg=True
  
  ans=0
  
  
  for _ in range(I()):
      n,k,x=LI()
      x-=1
      s=input()
      if s.count('*')==0:
          print(s)
          continue
      g=groupby(s)
      b=[[k,0,len(list(it))] for k,it in g]
      s=[[c,t,mb,None] for c,t,mb in b if c=='*']
      t=1
      i=j=0
      for c,_,mb,_ in s[::-1]:
          t*=mb*k+1
          #show(t)
          if t>x:
              j=i
          i+=1
          s[-i][-1]=mb*k+1
      #show('j',j)
      for i in range(-1,-j-2,-1):
          c,t,mb,com=s[i]
          s[i][1]=x%com
          x//=com
          #show(i,'I')
      #show(s)
      ans=[]
      j=0
      for k,_,no in b:
          if k=='a':
              ans+='a'*no,
          else:
              ans+='b'*s[j][1],
              j+=1
      #show(ans)
      print(''.join(ans))