T=int(input())
for _ in range(T):
    N=int(input())
    S=input()
    ans=-1

    key="helloworld"

    for i in range(N-9):
        flag=True
        for j in range(10):
            if not (S[i+j]=="?" or S[i+j]==key[j]):
                flag=False
                break
        if flag:
            ans=max(ans,i)
    if ans==-1:
        print(-1)
    else:
        ans2=[a for a in S.replace("?","a")]
        for j in range(10):
            ans2[j+ans]=key[j]
        print(*ans2,sep="")