HW = 'helloworld'
for _ in range(int(input())):
    n = int(input())
    s = input()
    for i in range(n - 10, -1, -1):
        for k in range(10):
            if s[i + k] != '?' and s[i + k] != HW[k]:
                break
        else:
            print(s[:i].replace('?', 'a') + HW + s[i + 10:].replace('?', 'a'))
            break
    else:
        print(-1)