from sys import stdin
input = stdin.readline

H = "helloworld"

for _ in range(int(input())):
    N = int(input())
    S = list(input().rstrip("\n"))

    flag = False
    for i in reversed(range(N-9)):
        if S[i:i+10] == list(H):
            flag = True
            for j in range(N):
                if S[j] == "?":
                    S[j] = "a"
            break
    if flag:
        print("".join(S))
        continue

    for i in reversed(range(N-9)):
        for j in range(10):
            if S[i+j] != "?" and S[i+j] != H[j]:
                break
        else:
            for j in range(10):
                S[i+j] = H[j]
            break
    else:
        print(-1)
        continue

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

    print("".join(S))