/* -*- coding: utf-8 -*-
 *
 * 1534.cc:  No.1534 おなかがいたい - yukicoder
 */

#include<cstdio>
#include<cstdlib>
#include<cstring>
#include<cmath>
#include<iostream>
#include<string>
#include<vector>
#include<map>
#include<set>
#include<stack>
#include<list>
#include<queue>
#include<deque>
#include<algorithm>
#include<numeric>
#include<utility>
#include<complex>
#include<functional>
 
using namespace std;

/* constant */

const int MAX_N = 200000;

/* typedef */

/* global variables */

char s[MAX_N + 4];

/* subroutines */

/* main */

int main() {
  scanf("%s", s);
  int n = strlen(s);

  char *ept = strstr(s, "pain");
  if (ept == nullptr) { puts("-1"); return 0; }

  int cnt = 0;
  for (char *cpt = s;;) {
    cpt = strstr(cpt, "pon");
    if (cpt == nullptr || cpt > ept) break;
    cnt++;
    cpt++;
  }

  printf("%d\n", (cnt < 2) ? 0 : cnt - 1);
  return 0;
}