hello = "helloworld"

def solve():
    n = int(input())
    S = input()

    ans = "{"
    for i in range(n-9):
        ok = 1
        for j in range(10):
            if S[i+j] != "?" and S[i+j] != hello[j]:
                ok = 0

        if ok == 0:
            continue

        cand = []
        for j,s in enumerate(S):
            if i <= j < i+10:
                cand.append(hello[j-i])
            else:
                if s == "?":
                    s = "a"
                cand.append(s)

        cand = "".join(cand)
        if cand < ans:
            ans = cand
    if ans == "{":
        ans = -1
    return ans      

t = int(input())
for _ in range(t):
    print(solve())