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

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