helloworld = "helloworld"
for _ in range(int(input())):
    n = int(input())
    S = list(input())
    if helloworld in ''.join(S):
        for i in range(n):
            if S[i] == '?':
                S[i] = 'a'
        print(''.join(S))
        continue
    for i in range(n - 9):
        flag = True
        for j in range(10):
            if S[i + j] == '?':
                continue
            if S[i + j] == helloworld[j]:
                continue
            flag = False
            break
        if flag:
            for j in range(10):
                if S[i + j] == '?':
                    S[i + j] = helloworld[j]
            for j in range(n):
                if S[j] == '?':
                    S[j] = 'a'
            break
    if flag:
        print(''.join(S))
    else:
        print(-1)