Problem:
Score : 300 points

Problem Statement

AtCoDeer the deer and his friend TopCoDeer is playing a game.
The game consists of N turns.
In each turn, each player plays one of the two gestures, Rock and Paper, as in Rock-paper-scissors, under the following condition:

(※) After each turn, (the number of times the player has played Paper)≦(the number of times the player has played Rock).

Each player's score is calculated by (the number of turns where the player wins) - (the number of turns where the player loses), where the outcome of each turn is determined by the rules of Rock-paper-scissors.

(For those who are not familiar with Rock-paper-scissors: If one player plays Rock and the other plays Paper, the latter player will win and the former player will lose. If both players play the same gesture, the round is a tie and neither player will win nor lose.)

With his supernatural power, AtCoDeer was able to foresee the gesture that TopCoDeer will play in each of the N turns, before the game starts.
Plan AtCoDeer's gesture in each turn to maximize AtCoDeer's score.

The gesture that TopCoDeer will play in each turn is given by a string s. If the i-th (1≦i≦N) character in s is g, TopCoDeer will play Rock in the i-th turn. Similarly, if the i-th (1≦i≦N) character of s in p, TopCoDeer will play Paper in the i-th turn.

Constraints

1≦N≦10^5

N=|s|

Each character in s is g or p.

The gestures represented by s satisfy the condition (※).

Input

The input is given from Standard Input in the following format:

s

Output

Print the AtCoDeer's maximum possible score.

Sample Input 1

gpg

Sample Output 1

0

Playing the same gesture as the opponent in each turn results in the score of 0, which is the maximum possible score.

Sample Input 2

ggppgggpgg

Sample Output 2

2

For example, consider playing gestures in the following order: Rock, Paper, Rock, Paper, Rock, Rock, Paper, Paper, Rock, Paper. This strategy earns three victories and suffers one defeat, resulting in the score of 2, which is the maximum possible score.

Solution in C# (Mono 4.6.2.0) (judge verdict: Wrong Answer)

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

namespace AtCoder
{
	class Program
	{
		static void Main(string[] args)
		{
			var s = Console.ReadLine();
			var sLength = s.Length;

			var points = new List<List<int>>();

			for(int i = 0; i < sLength; i++)
			{
				points.Add(new List<int>());
				for (int j = 0; j < sLength; j++)
				{
					points[i].Add(0);
				}
			}

			for (int pTimes = 0; pTimes <= sLength / 2; pTimes++)
			{
				var indexStart = pTimes != 0 ? pTimes * 2 - 1 : 0;
				for (int index = indexStart; index < indexStart + 2; index++)
				{
					if(index >= sLength)
					{
						break;
					}

					if(s[index] == 'g')
					{
						if(index == 0 && pTimes == 0)
						{
							points[pTimes][index] = 0;
							continue;
						}

						if(pTimes == 0)
						{
							points[pTimes][index] = points[pTimes][index - 1];
							continue;
						}

						points[pTimes][index] = points[pTimes - 1][index - 1] + 1;
					}
					else
					{
						if (index == 0 && pTimes == 0)
						{
							points[index][pTimes] = -1;
							continue;
						}

						if (pTimes == 0)
						{
							points[pTimes][index] = points[pTimes][index - 1] - 1;
							continue;
						}

						points[pTimes][index] = points[pTimes - 1][index - 1];
					}
				}
			}
			
			Console.WriteLine(points[sLength / 2][sLength - 1]);
		}
	}
}