#include <bits/stdc++.h>
#define NIL (-1)
#define ll long long
using namespace std;
const double PI = acos(-1.0);

int main() {
	string S;
	cin >> S;

	int s = S.find("pain");
	if (s == string::npos) {
		cout << -1 << endl;
		return 0;
	}
	//cout << s << endl;
	string T = S.substr(0, s);
	//cout << T.size() - 2 << endl;
	if (T.size() < 3) {
		cout << -1 << endl;
		return 0;
	}

	int co = 0;
	for (int i = 0; i < T.size()-2; i++) {
		string t = T.substr(i, 3);
		if (t == "pon") co++;
	}
	if (co < 2) {
		cout << -1 << endl;
		return 0;
	}
	cout << co - 1 << endl;

	return 0;
}