# 全探索して複数候補がある場合はできるだけ後ろにhelloworldをおいて余った?にはaをあてがう

T = int(input())

word = "helloworld"
num = len(word)

for _ in range(T):

    N = int(input())
    S = list(input())

    idx = -1
    for s in range(N-num,-1,-1):
        if S[s] != "h" and S[s] != "?":
            continue

        if all(S[s+i] == word[i] or S[s+i] == "?" for i in range(num)):
            idx = s
            break

    if idx == -1:
        print(-1)
        continue

    for i in range(num):
        if S[idx+i] == "?":
            S[idx+i] = word[i]

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

    print("".join(S))