#include <bits/stdc++.h>
using namespace std;
int main() {
  string s;
  cin >> s;
  int ans = 0;
  bool ok = false;
  for (int i = 0; i < s.size(); i++) {
    if (i + 3 < s.size() && s[i] == 'p' && s[i + 1] == 'a' && s[i + 2] == 'i' && s[i + 3] == 'n') {
      ok = true;
      break;
    }
    if (s[i] == 'p' && s[i + 1] == 'o' && s[i + 2] == 'n') {
      ans++;
    }
  }
  if (ok) ans = max(ans - 1 , 0);
  else ans = -1;
  cout << ans << endl;
  return 0;
}