#include <bits/stdc++.h>

using namespace std;

#define REP(i, n) for(int i = 0; i < n; i++)

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