#include <bits/stdc++.h>
#include <atcoder/all>
using namespace std;
using namespace atcoder;
using ll = long long;
using ull = unsigned long long;
using ld = long double;
using pii = pair<int, int>;
using pdd = pair<double, double>;
using pll = pair<ll, ll>;
using pli = pair<ll, int>;
using pil = pair<int, ll>;
template <typename T>
using Graph = vector<vector<T>>;
const int MOD = 1e9 + 7;
const ld PI = acos(-1);

int main() {
    cin.tie(0);
    ios::sync_with_stdio(false);

    string S;
    cin >> S;
    int cnt = 0;
    bool isok = false;
    for (int i = 0; i < S.size(); ++i) {
        if (i <= S.size() - 3 && S.substr(i, 3) == "pon") {
            cnt++;
        }
        if (i <= S.size() - 4 && S.substr(i, 4) == "pain") {
            isok = true;
            break;
        }
    }

    if (!isok || cnt < 2) {
        cout << -1 << endl;
    } else {
        cout << cnt - 1 << endl;
    }

    return 0;
}