#include <bits/stdc++.h>
#define rep(i,n) for(int i=0;i<n;i++)
//#define int long long
using namespace std;

string S;

signed main()
{
	cin >> S;
	int ans = 0;
	rep(i,S.length()) {
		if (S[i] == 'n') ans++;
	}
	cout << ans << endl;
}