hw = list("helloworld")
def solve():
  n = int(input())
  s = input()
  p = []
  q = []
  h = []
  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 s[i] == "h":
        h.append(i)
      else:
        q.append(i)
  if not p:
    print(-1)
    return
  for i in range(len(p)):
    pi = p[i]
    flg = 1
    for j in range(10):
      if s[pi+j] == "?":
        flg = 0
    if flg:
      st = []
      for j in range(n):
        if s[j] == "?":
          st.append("a")
        else:
          st.append(s[j])
      print("".join(st))
      break
  else:
    st = []
    pi = p[-1]
    for i in range(pi):
      if s[i] == "?":
        st.append("a")
      else:
        st.append(s[i])
    st += hw
    for i in range(pi+10, n):
      if s[i] == "?":
        st.append("a")
      else:
        st.append(s[i])
    print("".join(st))
  return 

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