#include <bits/stdc++.h>
using namespace std;

string s;
int n = -1;
bool f;

int main()
{
	cin >> s;

	for (int i = 0; i < s.size(); i++) {
		if (s.substr(i, 3) == "pon") {
			n++;
			i += 2;
		}
		else if (s.substr(i, 4) == "pain") {
			f = 1;
			break;
		}
	}
	
	if (f)
		cout << n << endl;
	else
		cout << -1 << endl;
}