for _ in range(int(input())):
    n = int(input())
    s = input()
    t = "helloworld"
    ans = "-1"
    for i in range(n-10,-1,-1):
        if t in s: ans = s; break
        if s[i-9:i+1]==t[:9]+"?": ans = s[:i-9]+t+s[i+1:]; break
        f = s[i-1:i]=="h"
        for j in range(9):
            if "?"!=s[i+j]!=t[j+1]: f = False
        if f: ans = s[:i-1]+t+s[i+9:]; break
        f = True
        for j in range(10):
            if "?"!=s[i+j]!=t[j]: f = False
        if f: ans = s[:i]+t+s[i+10:]; break
    print(ans.replace("?","a"))