#include <bits/stdc++.h>
using namespace std;
string a;
int main() {
  cin >> a;
  int x = 0, y = 0, ans = 0;
  for (int i = 0; i < a.length(); ++i) {
    if (x == y) {
      x++;
      if (a[i] == 'p') ans--;
    } else {
      y++;
      if (a[i] == 'g') ans++;
    }
  }
  printf("%d\n", ans);
  return 0;
}
