helloworld = "helloworld"
for _ in range(int(input())):
    n = int(input())
    S = list(input())
    ANS = []
    for i in range(n - 9):
        SC = S[:]
        flag = True
        for j in range(10):
            if SC[i + j] == '?':
                continue
            if SC[i + j] == helloworld[j]:
                continue
            flag = False
            break
        if flag:
            for j in range(10):
                if SC[i + j] == '?':
                    SC[i + j] = helloworld[j]
            for j in range(n):
                if SC[j] == '?':
                    SC[j] = 'a'
            ANS.append(''.join(SC))
    if len(ANS) == 0:
        print(-1)
    else:
        ANS.sort()
        print(ANS[0])