#pragma warning disable

using System;
using System.Collections.Generic;
using System.IO;
using System.Linq;
using System.Runtime.Serialization.Formatters.Binary;
using System.Text;
using System.Text.RegularExpressions;
using System.Diagnostics;
using System.Numerics;
using System.Collections;

static class MainClass
{
    public static void Main(string[] args)
    {

        var str = Console.ReadLine();
        var gcount = 0;
        var pcount = 0;
        var score = 0;

        for (int i = 0; i < str.Length; i++)
        {
            if (i == 0)
            {
                gcount++;
                if (str[i] == 'p')
                    score--;
            }
            else
            {
                if (gcount - 1 >= pcount)
                {

                    pcount++;
                    if (str[i] == 'g')
                        score++;
                }
                else
                {
                    gcount++;
                    if (str[i] == 'p')
                    {
                        score--;
                    }
                }
            }
        }
        Console.WriteLine(score);
        Console.ReadLine();
    }

    public static long f(long n,long b)
    {
        if (n < b)
        {
            return n;
        }
        else
        {
            return f((long)Math.Floor((double)n/b),b) + n % b;
        }
    }

    public static string N(long n,long b)
    {
        var sb = new StringBuilder();
        while (true)
        {
            sb.Append((n % b).ToString());
            n /= b;
            if (n < b)
            {
                sb.Append(n.ToString());
                break;
            }
        }
        return new string( sb.ToString().Reverse().ToArray() );
    }

    #region ライブラリ
    public static long ToInt64(this string str) => long.Parse(str);
    public static int ToInt32(this string str) => int.Parse(str);
    public static BigInteger ToBigInteger(this string str) => BigInteger.Parse(str);
    public static List<string> SplittedStringToList(this string str) => str.Split(new[] { ' ' }, StringSplitOptions.RemoveEmptyEntries).ToList();
    public static List<int> SplittedStringToInt32List(this string str) => str.Split(new[] { ' ' }, StringSplitOptions.RemoveEmptyEntries).Select(x => int.Parse(x)).ToList();
    public static List<long> SplittedStringToInt64List(this string str) => str.Split(new[] { ' ' }, StringSplitOptions.RemoveEmptyEntries).Select(x => long.Parse(x)).ToList();
    public static List<BigInteger> SplittedStringToBigInteger(this string str) => str.Split(new[] { ' ' }, StringSplitOptions.RemoveEmptyEntries).Select(x => BigInteger.Parse(x)).ToList();
    public const int INF = int.MaxValue / 2;
    public const long LONGINF = long.MaxValue / 2;
    public const int Mod1e9 = 1000000007;
    

    public static void PrintArray(int[,] array)
    {
        for (int i = 0; i < array.GetLength(0); i++)
        {
            var sb = new StringBuilder();
            for (int j = 0; j < array.GetLength(1); j++)
            {
                sb.Append(array[i, j]).Append(" ");
            }
            Console.WriteLine(sb.ToString());
        }
    }

    #endregion
}



Measured memory_bytes: 13212