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:
    if ''.join(case_s).count(''.join(hello)) > 0:
        for j in range(len(case_s)):
            if case_s[j] == '?':
                case_s[j] = 'a'
        print(''.join(case_s))
        continue

    possible = False
    for i in range(len(case_s) - 10, -1, -1):
        partial_possible = True
        for j in range(10):
            if case_s[i + j] != '?' and case_s[i + j] != hello[j]:
                partial_possible = False
        if partial_possible:
            # もう１つ前がhなら再チェック
            before_replace = False
            if i - 1 >= 0 and case_s[i - 1] == 'h':
                partial_possible = True
                for j in range(10):
                    if case_s[i + j - 1] != '?' and case_s[i + j - 1] != hello[j]:
                        partial_possible = False
                if partial_possible:
                    before_replace = True
            if before_replace:
                for j in range(10):
                    if case_s[i + j - 1] == '?':
                        case_s[i + j - 1] = hello[j]
                possible = True
                for j in range(len(case_s)):
                    if case_s[j] == '?':
                        case_s[j] = 'a'
            else:
                for j in range(10):
                    if case_s[i + j] == '?':
                        case_s[i + j] = hello[j]
                possible = True
                for j in range(len(case_s)):
                    if case_s[j] == '?':
                        case_s[j] = 'a'
        if possible:
            print(''.join(case_s))
            break
    if not possible:
        print(-1)