#include <iostream>
using namespace std;

string hello = "helloworld";

int main()
{
    int t;
    cin >> t;
    while (t--)
    {
        int n;
        string s;
        cin >> n >> s;
        string ans = "{";
        for (int i = 0; i < n - 9; i++)
        {
            bool f = true;
            for (int j = 0; j < 10; j++)
            {
                if (s[i + j] != '?' && s[i + j] != hello[j])
                {
                    f = false;
                    break;
                }
            }
            if (f)
            {
                string t = s;
                for (int j = 0; j < n; j++)
                {
                    if (t[j] == '?')
                    {
                        t[j] = 'a';
                    }
                }
                for (int j = 0; j < 10; j++)
                {
                    t[i + j] = hello[j];
                }
                ans = min(ans, t);
            }
        }
        if (ans == "{")
        {
            cout << -1 << endl;
        }
        else
        {
            cout << ans << endl;
        }
    }
}