hw = list("helloworld")
def solve():
  n = int(input())
  s = input()
  
  for i in range(0,n-10+1)[::-1]:
    flg = 1
    for j in range(10):
      if s[i+j] == hw[j] or s[i+j] == "?": continue
      flg = 0
    if flg:
      ans = []
      for j in range(i):
        if s[j] == "?":
          ans.append("a")
        else:
          ans.append(s[j])
      ans += hw
      for j in range(i+10,n):
        if s[j] == "?":
          ans.append("a")
        else:
          ans.append(s[j])
      print("".join(ans))
      break
  else:
    print(-1)


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