hw = list("helloworld")
def solve():
  n = int(input())
  s = input()
  p = []
  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
  st = []
  for i in range(n):
    if s[i] == "?":
      st.append("a")
    else:
      st.append(s[i])
  for i in range(len(p)):
    pi = p[i]
    if i == len(p) - 1:
      for j in range(10):
        st[pi+j] = hw[j]
      print("".join(st))
    else:
      if s[pi] == "?": continue
      for j in range(10):
        st[pi+j] = hw[j]
      print("".join(st))
      break
  return 

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