#include <iostream>
#include <string>
using namespace std;

int main(){
    string s;
    cin >> s;
    int ans = 0;
    bool painexist = false;
    for(int i = 0; i < s.length(); i++){
        if(s.substr(i, 4) == "pain"){
            painexist = true;
            break;
        }else if(s.substr(i, 3) == "pon") ans++;
    }

    if(!painexist || ans < 2) cout << -1 << endl;
    else cout << ans-1 << endl;
    return 0;
}