T=int(input())
W='helloworld'
for _ in range(T):
  N=int(input())
  S=list(input())
  A=[]
  for i in range(N-9):
    SS=S.copy()
    f=0
    for j in range(10):
      if SS[i+j]!=W[j] and SS[i+j]!='?':
        f=1
        break 
      if SS[i+j]=='?':
        SS[i+j]=W[j]
    if f==0:
      SS=''.join(SS)
      SS=SS.replace('?','a')
      A.append(SS)
  if len(A)==0:
    print(-1)
  else:
    print(sorted(A)[0])