#include<bits/stdc++.h>
using namespace std;
#define rep(i,a,b) for(int i=a;i<b;i++)

/*
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                                      Welcome To My Coding Space!
*/


string s;
//-----------------------------------------------------------------
int main() {
    cin >> s;
    int ans = 0;
    for (char c : s) if (c == 'n') ans++;
    cout << ans << endl;
}