output_description: Print the AtCoDeer's maximum possible score.
  
  * * *
input_description: The input is given from Standard Input in the following format:
  
      
      
      s
attempt: import sys, collections as cl, bisect as bs
  
  sys.setrecursionlimit(100000)
  input = sys.stdin.readline
  mod = 10**9 + 7
  Max = sys.maxsize
  
  
  def l():  # intのlist
      return list(map(int, input().split()))
  
  
  def m():  # 複数文字
      return map(int, input().split())
  
  
  def onem():  # Nとかの取得
      return int(input())
  
  
  def s(x):  # 圧縮
      a = []
      if len(x) == 0:
          return []
      aa = x[0]
      su = 1
      for i in range(len(x) - 1):
          if aa != x[i + 1]:
              a.append([aa, su])
              aa = x[i + 1]
              su = 1
          else:
              su += 1
      a.append([aa, su])
      return a
  
  
  def jo(x):  # listをスペースごとに分ける
      return " ".join(map(str, x))
  
  
  def max2(x):  # 他のときもどうように作成可能
      return max(map(max, x))
  
  
  def In(x, a):  # aがリスト(sorted)
      k = bs.bisect_left(a, x)
      if k != len(a) and a[k] == x:
          return True
      else:
          return False
  
  
  def pow_k(x, n):
      ans = 1
      while n:
          if n % 2:
              ans *= x
          x *= x
          n >>= 1
      return ans
  
  
  """
  def nibu(x,n,r):
      ll = 0
      rr = r
      while True:
          mid = (ll+rr)//2
  
      if rr == mid:
          return ll
      if (ここに評価入れる):
          rr = mid
      else:
          ll = mid+1
  """
  
  s = input()[:-1]
  
  po = 0
  
  for i in range(len(s)):
      if s[i] == "p":
          po += 1
  
  
  print(len(s) // 2 - po)
  
problem_description: 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.
samples: [{"input": "gpg", "output": "0\n    \n\nPlaying the same gesture as the opponent in each turn results in the score of\n0, which is the maximum possible score.\n\n* * *"}, {"input": "ggppgggpgg", "output": "2\n    \n\nFor example, consider playing gestures in the following order: Rock, Paper,\nRock, Paper, Rock, Rock, Paper, Paper, Rock, Paper. This strategy earns three\nvictories and suffers one defeat, resulting in the score of 2, which is the\nmaximum possible score."}]