#include <bits/stdc++.h>
#include <atcoder/all>
using namespace std;
using namespace atcoder;
using ll = long long;
using ld = long double;

int main() {
  string S; cin >> S;
  int pos = S.find("pain");
  if (pos == -1) cout << -1 << endl;
  else {
    int cnt = 0;
    for (int i = 0; i <= pos - 3; i++) {
      if (S.substr(i, 3) == "pon") cnt++;
    }
    if (cnt < 2) cout << -1 << endl;
    else cout << cnt - 1 << endl;
  }
  return 0;
}