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