#include <cmath>
#include <deque>
#include <algorithm>
#include <iterator>
#include <list>
#include <tuple>
#include <map>
#include <unordered_map>
#include <queue>
#include <set>
#include <unordered_set>
#include <stack>
#include <string>
#include <vector>
#include <fstream>
#include <iostream>
#include <functional>
#include <numeric>
#include <iomanip> 
#include <stdio.h>
//eolibraries
#define lnf 3999999999999999999
#define inf 999999999
#define PI 3.14159265359
#define endl "\n"
#define fi first
#define se second
#define pb push_back
#define eb emplace_back
#define ll long long
#define all(c) (c).begin(),(c).end()
#define sz(c) (int)(c).size()
#define mkp(a,b) make_pair(a,b)
#define make_unique(a) sort(all(a)),a.erase(unique(all(a)),a.end())
#define rsz(a,n) a.resize(n)
#define pii pair <int,int>
#define rep(i,n) for(int i = 0 ; i < n ; i++) 
#define drep(i,n) for(int i = n-1 ; i >= 0 ; i--)
#define crep(i,x,n) for(int i = x ; i < n ; i++)
#define vi vector <int> 
#define vec(s) vector<s>
#define rsz(a,n) a.resize(n)
#define rszv(a,n,v) a.resize(n,v)
#define fcin ios_base::sync_with_stdio(false),cin.tie(0),cout.tie(0);
//eodefine
 
const int max_n = 103002;
 
using namespace std;

int main(){
fcin;
	string s;
	cin>>s;
	int c=0;
	rep(i,sz(s)) {
		if(i+2<sz(s)) {
			if(s.substr(i,3) == "pon")c++;
		}
		if(i+3<sz(s)) {
			if(s.substr(i,4) == "pain") { 
				if(c>=2)cout<<c-1<<"\n";
				else cout<<"-1\n";
				exit(0);
			} 
		}
	}

	cout<<"-1\n";
 
/*
*/
 
    return 0;   
}