D - AtCoDeerくんと変なじゃんけん 解説 /

実行時間制限: 2 sec / メモリ制限: 256 MB

配点 : 300


シカのAtCoDeerくんは友達のTopCoDeerくんとあるゲームをして対戦しています。 このゲームは N ターンからなります。各ターンではそれぞれのプレイヤーはじゃんけんのグーかパーを出します。ただし、各プレイヤーは次の条件を満たす必要があります。

(※) 各ターンの後で、(今までにパーを出した回数)(今までにグーを出した回数) を満たす

このゲームでの各プレイヤーの得点は、(勝ったターンの数) - (負けたターンの数) です。 AtCoDeerくんは特殊能力を持っているので、ゲームが始まる前にTopCoDeerくんの出す N ターンの手を全て知ることが出来ました。 AtCoDeerくんの各ターンでの手を決めて、AtCoDeerくんの得点を最大化してください。 TopCoDeerくんの出す手の情報は文字列 s で与えられます。 si(1≦i≦N) 文字目が gのときは i ターン目でTopCoDeerくんがグーを出すことを、 pのときはパーを出すことを表します。


  • 1≦N≦10^5
  • N=|s|
  • s の各文字はgp
  • s で表される手は、条件(※)を満たしている






入力例 1


出力例 1



入力例 2


出力例 2


例えばグー,パー,グー,パー,グー,グー,パー,パー,グー,パー と出すことで、 3回勝って1回負けているので得点は2点になり、これが最大値です。

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.


  • 1≦N≦10^5
  • N=|s|
  • Each character in s is g or p.
  • The gestures represented by s satisfy the condition (※).


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



Print the AtCoDeer's maximum possible score.

Sample Input 1


Sample Output 1


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


Sample Output 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.