def check(X, Y):
    for i in range(len(X)):
        if X[i] != Y[i] and X[i] != "?":
            return 0
    return 1

T = int(input())
hello = list("helloworld")
for _ in range(T):
    N = int(input())
    S = list(input())
    flag = 0
    for i in range(N - 10, -1, -1):
        if S[i:i+10] == hello:
            flag = 1
            break
    if flag:
        for i in range(N):
            if S[i] == "?":
                S[i] = "a"
        print("".join(S))
        continue
        
        
    for i in range(N - 10, -1, -1):
        if check(S[i:i+10], hello):
            S[i:i+10] = hello
            break
    else:
        print(-1)
        continue
    for i in range(N):
        if S[i] == "?":
            S[i] = "a"
    print("".join(S))