h = 'helloworld'
for _ in range(int(input())):
    n = int(input())
    s = list(input())
    ans = []
    for i in range(len(s) - len(h), -1, -1):
        flag = True
        for j in range(len(h)):
            if s[i + j] == '?' or s[i + j] == h[j]:
                continue
            else:
                flag = False
        if flag:
            t = s
            for j in range(len(h)):
                t[i + j] = h[j]
            ans.append(''.join(t).replace('?', 'a'))
    ans.sort()
    if ans:
        print(ans[0])
    else:
        print(-1)