#include <bits/stdc++.h>
#include<iostream>
#include<map>
#include<vector>
#include <algorithm>
#include<math.h>
#include <iomanip>
#include<set>
#include <numeric>
#include<string>
using ll = long long;
using namespace std;

int main()
{
    string s, p1 = "pon", p2 = "pain";
    ll cnt = 0, t;
    bool pain = false;
    cin >> s;
    int len = s.size();
    for (int i = 0; i < len; i++){
        if (s[i] == 'p'){
            if (s.substr(i, 3) == p1) cnt++;
            if (s.substr(i, 4) == p2){
            pain = true;
            break;
            }
        }
    }
    
    if (pain && cnt >= 2) cout << cnt - 1 << endl;
    else cout << -1 << endl;
}