T=int(input())
H="helloworld"
for i in range(T):
    N=int(input())
    S=list(map(str, input()))
    mem=[]
    for j in range(N-9):
        p=""
        l=0
        res=True
        for k in range(N):
            if j <= k <= j + 9:
                if S[k] == H[l] or S[k] == "?":
                    p += H[l]
                    l += 1
                else:
                    res=False
                    break
            else:
                if S[k] == "?":
                    p += "a"
                else:
                    p += S[k]
        
        if res:
            mem.append(p)
    
    mem=sorted(mem)
    if len(mem) > 0:
        print(mem[0])
    else:
        print(-1)