using System;

public class Hello
{
    static void Main()
    {
        var s = Console.ReadLine().Trim();
        getAns(s);
    }
    static void getAns(string s)
    {
        var p = s.IndexOf("pain");
        if (p == -1) { Console.WriteLine(-1); return; }
        var t = s.Substring(0, p);
        var tL = t.Length;
        var ans = (tL - t.Replace("pon", "").Length) / 3 - 1;
        Console.WriteLine(ans == 0 ? -1 : ans);
    }
}