#include <bits/stdc++.h>
#define rep(i, n) for (int i = 0; i < n; ++i)
typedef long long ll;
using namespace std;

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

    bool flag = false;
    int cnt = 0;
    rep(i, S.size()) {
        if (S.compare(i, 3, "pon") == 0)
            cnt++;
        else if (S.compare(i, 4, "pain") == 0) {
            flag = true;
            break;
        }
    }

    if (flag) {
        if (cnt < 2)
            cout << -1;
        else
            cout << cnt - 1;
    } else {
        cout << -1;
    }
    cout << endl;

    return 0;
}