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 (GCC 5.4.1) (judge verdict: Runtime Error)

#include <stdio.h>
#include <string.h>
#define FOR(i, a, b) for(i = a; i < b; ++i)
#define REP(i, n) FOR(i, 0, n)

#define N 100000

int result(char atc, char topc){
    if(atc == 'p' && topc == 'g'){
        return 1;
    }else if(atc == 'g' && topc == 'p'){
        return -1;
    }else{
        return 0;
    }
}

int max(int a, int b){
    return a > b? a : b;
}

int rock_paper(unsigned int n, unsigned int p, unsigned int len, int dp[len + 1][len + 1], char S[N]){
    if(dp[n][p] != -N){
        return dp[n][p];
    }
    if(n == len){
        return dp[n][p] = 0;
    }

    int rock = rock_paper(n + 1, p + 1, len, dp, S) + result('g', S[n]);
    if(p == 0){
        return dp[n][p] = rock;
    }else{
        int paper = rock_paper(n + 1, p - 1, len, dp, S) + result('p', S[n]);
        return dp[n][p] = max(rock, paper);
    }
}

int main(){
    char S[N];
    scanf("%s", S);
    unsigned int len = strlen(S);
    int dp[len + 1][len + 1];
    unsigned int i, j;

    if(len == 1){
        if(S[0] == 'p'){
            printf("-1\n");
        }else{
            printf("0\n");
        }
    }
    else{
        REP(i, len + 1){
            REP(j, len + 1){
                dp[i][j] = -N;
            }
        }
        printf("%d\n", rock_paper(0, 0, len, dp, S));
        /*
        REP(i, len + 1){
            REP(j, len + 1){
                printf("%d ", dp[i][j]);
            }
            printf("\n");
        }
        */

    }
    return 0;
}

/*
nターン目以降を最適化した時の最大化された点数：dp[n][p]
n:何ターン目か, p:パーを出せる回数の上限
*/