#include <bits/stdc++.h>
using namespace std;
int main(){
  string S;
  cin >> S;
  int N = S.size();
  int X = -1;
  for (int i = 0; i <= N - 4; i++){
    if (S.substr(i, 4) == "pain"){
      X = i;
      break;
    }
  }
  if (X == -1){
    cout << -1 << endl;
  } else {
    int cnt = 0;
    for (int i = 0; i <= X - 3; i++){
      if (S.substr(i, 3) == "pon"){
        cnt++;
      }
    }
    if (cnt < 2){
      cout << -1 << endl;
    } else {
      cout << cnt - 1 << endl;
    }
  }
}