for _ in range(int(input())):
    n = int(input())
    s = input()
    t = "helloworld"
    ans = "z"*n
    for i in range(n-10,-1,-1):
        f = True
        for j in range(10):
            if "?"!=s[i+j]!=t[j]: f = False
        if f: ans = min(ans,s[:i]+t+s[i+10:])
    print(ans.replace("?","a") if ans!="z"*n else -1)