T = int(input())
for _ in range(T):
    N = int(input())
    S = str(input())
    
    ans = ''
    hello = 'helloworld'
    pos = False
    for i in range(N):
        ans += 'z'
    for i in range(N - 9):
        possub = True
        anssub = ''
        for j in range(10):
            if S[i + j] != '?' and S[i + j] != hello[j]:
                possub = False
        if possub:
            pos = True
            for j in range(N):
                if 0 <= j - i < 10:
                    anssub += hello[j - i]
                else:
                    if S[j] == '?':
                        anssub += 'a'
                    else:
                        anssub += S[j]
            if ans > anssub:
                ans = anssub
    if pos:
        print(ans)
    else:
        print(-1)