#include <bits/stdc++.h>
using namespace std;
using ll = long long;
const int INF = 1e+9;
const ll LINF = (ll)pow(10,18);

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

    string t;

    int idx = 1e+9;

    if(s.size() < 4){
        cout << -1 << endl;
        return 0;
    }

    for(int i=0; i<s.size()-3; i++){
        t = s.substr(i,4);
        if(t == "pain"){
            idx = i;
            break;
        }
    }

    if(idx == 1e+9){
        cout << -1 << endl;
        return 0;
    }

    int ans = 0;

    for(int i=0; i<idx; i++){
        t = s.substr(i,3);
        if(t == "pon") ans++;
    }

    if(ans < 2) cout << -1 << endl;
    else cout << ans - 1 << endl;
}