T = int(input())
U = "helloworld"

for _ in range(T):
    N = int(input())
    S = input()
    ans = list(S)
    flag = False
    for i in range(N-1,9-1,-1):
        if flag:
            if ans[i] == "?":
                ans[i] = "a"
            continue
        for j in range(10):
            f = True
            if S[i-j] == "?" or S[i-j] == U[9-j]:
                pass
            else:
                f = False
                break
        if f:
            flag = True
            for j in range(10):
                ans[i-j] = U[9-j]
        else:
            if ans[i] == "?":
                ans[i] = "a"
    if flag:
        for i in range(min(9,len(ans))):
            if ans[i] == "?":
                ans[i] = "a"
        print("".join(ans))
    else:
        print(-1)