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

int main(){
	string s;
    cin >> s;
    int count = 0;
    for (int i = 0; i < s.size()-3; i++) {
    if (s.at(i) == 'Z'){
    	if (s.at(i+1) =='O'){
        	if (s.at(i+2) =='N'){
        		if (s.at(i+3) =='e'){
        			count++;
     		    }
	        }  
        }
    }       
    }
	cout << count <<endl;

}
//                        YATIN KWATRA

#include <bits/stdc++.h>
#include <ext/pb_ds/assoc_container.hpp>
#include <ext/pb_ds/tree_policy.hpp>

#define ll                      long long
#define ar                      array
#define sz(v)                   (int)(v.size())
#define inf                     1e18
#define int                     ll
#define FIO                     ios_base::sync_with_stdio(0);cin.tie(0);cout.tie(0);
#define ld                      long double
#define ull                     unsigned long long
#define endl                    "\n"
#define fo(i,a,b)               for(int i = a; i<=b ; i++)
#define rfo(i,a,b)              for(int i = a; i>=b ; i--)
#define vii                     vector<int>
#define pq                      priority_queue
#define uomii                   unordered_map<int,int,best_hash>
#define all(v)                  v.begin(),v.end()
#define mp                      make_pair
#define pb                      push_back
#define pob                     pop_back
#define ff                      first
#define ss                      second
#define pii                     pair<int,int>
#define mii                     map<int,int>
#define vvii                    vector<vii>
#define mod                     1000000007
#define MIN                     -1e9
#define pi                      3.1415926535897932384626433832795
#define cz(x)                   63 - __builtin_clzll(x)

using namespace std;
using namespace __gnu_pbds;
template<class T> using oset =  tree<T, null_type, less<T>, rb_tree_tag, tree_order_statistics_node_update>;


struct best_hash {
	static uint64_t splitmix64(uint64_t x) {

		x += 0x9e3779b97f4a7c15;
		x = (x ^ (x >> 30)) * 0xbf58476d1ce4e5b9;
		x = (x ^ (x >> 27)) * 0x94d049bb133111eb;
		return x ^ (x >> 31);
	}

	size_t operator()(uint64_t x) const {
		static const uint64_t FIXED_RANDOM = chrono::steady_clock::now().time_since_epoch().count();
		return splitmix64(x + FIXED_RANDOM);
	}
};

void INPUT()
{
#ifndef ONLINE_JUDGE
	freopen("input.txt", "r", stdin);
	freopen("output.txt", "w", stdout);
#endif
}

/*
----------------------------------------------------------------
   -> Check For Overflows
   -> Out of Bounds
   -> Initialisations of global arrays and variables
----------------------------------------------------------------
*/


void solve()
{
	string s;
	cin >> s;
	int n = sz(s);
	int ans = 0;
	fo(i, 3, n - 1) {
		if (s.substr(i - 3, 4) == "ZONe") ans++;
	}
	cout << ans;
}

signed main() {

	FIO
	INPUT();

	int t;
	t = 1;
	//cin >> t;
	fo(i, 0, t - 1) {
		solve();
	}
	return 0;
}
