using System;
using System.Linq;

class I
{
	static void Main() => Console.WriteLine(Solve());
	static object Solve()
	{
		var n = int.Parse(Console.ReadLine());
		var s = Console.ReadLine();

		if (s.Count(c => c == 'Q') == 1 && !s.Contains('H')) return s;
		return -1;
	}
}