#include <iostream>
#include <string>
#include <algorithm>
using namespace std;
int main() {
	cin.tie(0); ios::sync_with_stdio(false);
	int tree = 0;
	string S;
	cin >> S;
	int len = S.length();
	for (int i = 0; i < len; i++) {
		if (S[i] == 'e') { tree++; }
	}
	cout << tree/2 << endl;
	return 0;
}