#include <bits/stdc++.h>
#define rep(i, n) for (int i = 0; i < n; ++i)
using ll = long long;
using namespace std;
const int INF = 1e9;
const int MOD = INF + 7;

int main() {
    int ans = 0;
    string s;
    cin >> s;

    rep(i, s.size()) if (s[i] == 'n')++ ans;

    cout << ans << endl;

    return 0;
}