/*input
helloAtZoner



*/
#include<bits/stdc++.h>
#include <ext/pb_ds/assoc_container.hpp>
#include <ext/pb_ds/tree_policy.hpp>
using namespace std;
using namespace __gnu_pbds;
typedef tree<long long,null_type,less_equal<long long>,rb_tree_tag,tree_order_statistics_node_update> indexed_set;
//order_of_key #of elements less than x
// find_by_order kth element
using ll=long long;
using ld=long double;
using pii=pair<ll,ll>;
#define f first
#define s second
#define pb push_back
#define REP(i,n) for(ll i=0;i<n;i++)
#define REP1(i,n) for(int i=1;i<=n;i++)
#define FILL(n,x) memset(n,x,sizeof(n))
#define ALL(_a) _a.begin(),_a.end()
#define sz(x) (int)x.size()
#define SORT_UNIQUE(c) (sort(c.begin(),c.end()),c.resize(distance(c.begin(),unique(c.begin(),c.end()))))
const ll INF64=4e18;
const int INF=0x3f3f3f3f;
const ll MOD=3;
const ld PI=acos(-1);
const ld eps=1e-9;
#define lowb(x) x&(-x)
#define MNTO(x,y) x=min(x,(__typeof__(x))y)
#define MXTO(x,y) x=max(x,(__typeof__(x))y)
inline ll mult(ll a,ll b){
    if(a>=MOD) a%=MOD;
    if(b>=MOD) b%=MOD;
    return (a*b)%MOD;
}
inline ll mypow(ll a,ll b){
    if(b<=0) return 1;
    ll res=1LL;
    while(b){
        if(b&1) res=mult(res,a);
        a=mult(a,a);
        b>>=1;
    }
    return res;
}
const int maxn=1e5+5;
int main(){
    ios::sync_with_stdio(false),cin.tie(0);
    string s;
    cin>>s;
    int ans=0;
    REP(i,sz(s)){
        string x="";
        REP(j,4) x.pb(s[i+j]);
        if(x=="ZONe"){
            ++ans;
        }
    }
    cout<<ans;
}
#include<bits/stdc++.h>
using namespace std;
using ll = long long;

const ll mod = 1e9 + 7;

int run_test(){
  string s;
  cin >> s;
  int ans = 0;
  for(int i = 0; i <= 8; i++){
    if(s[i] == 'Z' && s[i+1] == 'O' && s[i+2] == 'N' && s[i+3] =='e'){
      ans++;
    }
  }
  cout << ans;
  return 0;
}

int main()
{
  ios::sync_with_stdio(0);
  cin.tie(0); cout.tie(0);
  int tt;
  tt = 1;
  while(tt--){
    run_test();
  }
}