import sys
from sys import stdin

TT = int(stdin.readline())
hw = "helloworld"

for loop in range(TT):

    N = int(stdin.readline())

    S = list(stdin.readline()[:-1])

    if hw in S:
        for i in range(N):
            if S[i] == "?":
                S[i] = "a"

        print ("".join(S))
        continue
    

    for i in range(N-10,-1,-1):

        flag = True
        for j in range(10):

            if S[i+j] != "?" and S[i+j] != hw[j]:
                flag = False
                break

        if flag:
            for j in range(10):
                S[i+j] = hw[j]

            for j in range(N):
                if S[j] == "?":
                    S[j] = "a"

            print ("".join(S))
            break

    else:
        print (-1)