// 

import java.util.*;

public class Main {
    private static final String TAR = "helloworld";
    public static void main(String[] args) {
        final int TLEN = TAR.length();
        Scanner sc = new Scanner(System.in);
        int t0 = sc.nextInt();
        for (int i0=0; i0<t0; ++i0) {
            int n = sc.nextInt();
            String s = sc.next(), res = "";
            for (int i=0; i+TLEN-1<n; ++i) {
                boolean ok = true;
                for (int j=0; j<TLEN; ++j) if (s.charAt(i+j)!='?' && s.charAt(i+j)!=TAR.charAt(j)) {
                    ok = false;
                    break;
                }
                if (!ok) continue;
                String ts = new StringBuilder(s).replace(i, i+TLEN, TAR).toString().replace('?', 'a');
                if (res.isEmpty() || ts.compareTo(res)<0) res = ts;
            }
            if (res.isEmpty()) System.out.println(-1);
            else System.out.println(res);
        }
        sc.close();
    }
}