#include <bits/stdc++.h>
using namespace std;

#define FOR(i,l,r) for(int i = (l);i < (r);i++)
#define PB push_back
#define MP make_pair
#define ALL(x) (x).begin(),(x).end()
typedef long long ll;

string S;

int main()
{
	cin >> S;

	cout << count(ALL(S),'n') << endl;

	return 0;
}