#include <bits/stdc++.h>
using namespace std;

int main()
{
    string S;
    cin >> S;
    int N = S.size();
    int pain = -1;
    for (int i = 0; i < N - 3; i++)
    {
        if (S.substr(i, 4) == "pain")
        {
            pain = i;
            break;
        }
    }
    if (pain == -1)
    {
        cout << -1;
        return 0;
    }
    int pon = 0;
    for (int i = 0; i < pain - 2; i++)
    {
        if (S.substr(i, 3) == "pon")
        {
            pon++;
        }
    }
    if (pon < 2)
    {
        cout << -1;
    }
    else
    {
        cout << pon - 1;
    }
}