hw = list("helloworld")
def solve():
  n = int(input())
  s = input()
  p = []
  ords = []
  for i in range(n):
    if s[i] != "?":
      ords.append(ord(s[i]) - ord("a"))
    else:
      ords.append(-1)

  for i in range(0,n-10+1):
    flg = 1
    for j in range(10):
      if s[i+j] == hw[j] or s[i+j] == "?": continue
      flg = 0
    if flg:
      p.append(i)
  
  if not p:
    print(-1)
    return
  
  ss = []
  for i in range(len(p)):
    pi = p[-1]
    st = []
    for i in range(pi):
      if ords[i] == -1:
        st.append(0)
      else:
        st.append(ords[i])
    st += [7,4,11,11,14,22,14,17,11,3]
    for i in range(pi+10, n):
      if ords[i] == -1:
        st.append(0)
      else:
        st.append(ords[i])
    ss.append(st)
  ss.sort()
  ans = []
  for i in ss[0]:
    ans.append(chr(i + ord("a")))
  print("".join(ans))

  

t = int(input())
for i in range(t):
  solve()