from collections import defaultdict, deque
from sys import stdin

readline = stdin.readline


def li():
    return list(map(int, readline().split()))


T = int(input())
case_list = []
for _ in range(T):
    N = int(input())
    case_list.append(list(input()))

# 後ろから探して最初に見つけた場所をhelloworldにする
# 残りの?にはaを入れる
hello = list('helloworld')

for case_s in case_list:
    index = 9
    possible = False
    for i in range(len(case_s) - 1, -1, -1):
        if case_s[i] == '?' or case_s[i] == hello[index]:
            index -= 1
        else:
            if case_s[i] == '?' or case_s[i] == hello[9]:
                index = 8
            else:
                index = 9
        if index == -1:
            # helloworldを確定
            for j in range(10):
                case_s[i + j] = hello[j]
            for j in range(len(case_s)):
                if case_s[j] == '?':
                    case_s[j] = 'a'
            possible = True
            break

    if possible:
        print(''.join(case_s))
    else:
        print(-1)