#include <bits/stdc++.h>
using namespace std;
#ifdef LOCAL
  #include "settings/debug.cpp"
#else
  #define Debug(...) void(0)
#endif
#define rep(i, n) for (int i = 0; i < (n); ++i)
using ll = long long;
using ull = unsigned long long;

int main() {
  string s;
  cin >> s;
  int cnt = -1;
  bool has = false;
  rep(i, s.size()) {
    if (s.substr(i, 4) == "pain") {
      has = true;
      break;
    }
    if (s.substr(i, 3) == "pon") ++cnt;
  }
  cout << (cnt > 0 && has ? cnt : -1) << endl;
  return 0;
}