#include <iostream>
#include <string>
#include <vector>
#include <algorithm>
#include <queue>
#include <cmath>
#include <climits>
#include <iomanip>
#include <set>
#include <map>
using namespace std;
typedef long long ll;
int main(){
    string s;
    cin >> s;
    ll res = 0;
    for(int i = 0;i < (int)(s.size());i++){
        if(s[i] == 'n')res++;
    }
    cout << res << endl;
}