using System;
using System.Collections.Generic;
using System.Linq;

static class Ponponpain
{
    static void Main()
    {
		var s = Console.ReadLine();
		var endIndex = s.IndexOf("ponpain");
		if(endIndex <= 0)
			Console.WriteLine(-1);
		else
			Console.WriteLine(s.Substring(0, endIndex).Split('p').Where(x => x.StartsWith("on")).Count());
	}
}