#include "bits/stdc++.h"
#define int long long
using namespace std;
using ll = long long;
using P = pair<ll, ll>;
const ll INF = (1LL << 61);
ll mod = 998244353;

signed main() {
	ios::sync_with_stdio(false);
	cin.tie(0);
	string S; cin >> S;
	int N = S.size();
	int idx = -1;
	for (int i = 0; i < N - 3; i++) {
		if (S.substr(i, 4) == "pain") {
			idx = i;
			break;
		}
	}
	if (idx == -1) {
		cout << -1 << endl; return 0;
	}
	int cnt = 0;
	for (int i = 0; i < idx - 2; i++) {
		if (S.substr(i, 3) == "pon")cnt++;
	}
	if (cnt <= 1) {
		cout << -1 << endl; return 0;
	}
	else cout << cnt - 1<< endl;
	return 0;

}