#include <iostream>
#include <vector>
#include <string>
#include <set>
using namespace std;

void solve(int n, string s){
    const string hello = "helloworld";
    set<string> ans;
    for(int i = n-10; i >= 0; i--){
        bool isok = true;
        for(int j = 0; j < 10; j++){
            if(!(s[i+j] == '?' || s[i+j] == hello[j])) isok = false;
        }
        if(isok){
            string t = s;
            for(int j = 0; j < 10; j++) t[i+j] = hello[j];
            for(int j = 0; j < n; j++){
                if(t[j] == '?') t[j] = 'a';
            }
            ans.emplace(t);
        }
    }

    cout << (ans.empty() ? "-1" : *ans.begin()) << '\n';
}

int main(){
    int t; cin >> t;
    while(t--){
        int n; cin >> n;
        string s; cin >> s;
        solve(n, s);
    }
    return 0;
}