#include <iostream>
#include <vector>
#include <string>
#include <algorithm>
#include <utility>
#include <iomanip>
using namespace std;

int main(void) {
	int ans = 0;
	string str;
	cin >> str;
	for (int i = 0; i < str.size(); i++) {
		if (str[i] == 'n')
			ans++;
	}
	cout << ans << endl;
}