#include <algorithm>
#include <complex>
#include <cstdlib>
#include <ctime>
#include <time.h>
#include <iomanip>
#include <iostream>
#include <map>
#include <math.h>
#include <queue>
#include <random>
#include <set>
#include <sstream>
#include <stack>
#include <string>
#include <vector>
#include <numeric>
#include <limits>
#include <type_traits>
#include <locale>
#include <omp.h>
#include <string.h>

using namespace std;
#define SAY_YES cout << "YES" << endl;
#define SAY_Yes cout << "Yes" << endl;
#define SAY_NO cout << "NO" << endl;
#define SAY_No cout << "No" << endl;
#define IFYES(TRUE_OR_FALSE)   \
    if (TRUE_OR_FALSE)         \
    {                          \
        cout << "YES" << endl; \
    }                          \
    else                       \
    {                          \
        cout << "NO" << endl;  \
    }
#define IFYes(TRUE_OR_FALSE)   \
    if (TRUE_OR_FALSE)         \
    {                          \
        cout << "Yes" << endl; \
    }                          \
    else                       \
    {                          \
        cout << "No" << endl;  \
    }
#define IFyes(TRUE_OR_FALSE)   \
    if (TRUE_OR_FALSE)         \
    {                          \
        cout << "yes" << endl; \
    }                          \
    else                       \
    {                          \
        cout << "no" << endl;  \
    }
#define DEBUG_OUTPUT_ARRAY(XXX, ONE)                            \
    for (int i = 0; i < (ONE); i++)                             \
    {                                                           \
        cout << "DEBUG: i = " << i << " -> " << XXX[i] << endl; \
    }
#define DEBUG_OUTPUT_ARRAY2(XXX, ONE, TWO)                             \
    for (int i = 0; i < (ONE); i++)                                    \
    {                                                                  \
        cout << "<<< i = " << i << " >>>" << endl;                     \
        for (int j = 0; j < (TWO); j++)                                \
        {                                                              \
            cout << "DEBUG: j = " << j << " -> " << XXX[i][j] << endl; \
        }                                                              \
    }
#define DEBUG_OUTPUT_ARRAY2_BOX(XXX, ONE, TWO) \
    for (int i = 0; i < (ONE); i++)            \
    {                                          \
        cout << i << "  ";                     \
        for (int j = 0; j < (TWO); j++)        \
        {                                      \
            cout << XXX[i][j] << " ";          \
        }                                      \
        cout << endl;                          \
    }

typedef pair<long long int, long long int> pll;
typedef pair<long long int, pll> lpll;

bool overflow_checker(long long int input_number1,long long int input_number2){
    if(5000000000000000000/input_number1<input_number2){
        return true;
    }else{
        return false;
    }
}

const long long int mod = 1000000007;
const long long int INF = 2e18;
const long double PI=3.14159265358979323; 
const long long int pl=1100;
const long double eps =0.00001;

long long int N,M,K,res=0;
long long int A[202002],B[200200];
string S[200200],T;

int main(){

    cout << fixed << setprecision(18);

    cin>>T;
    for (long long int i = 0; i < T.size()-3; i++)
    {
        if(T.substr(i,4)=="ZONe"){
            res++;
        }
    }
    cout<<res<<endl;
    
    
}

#include<bits/stdc++.h>
using namespace std;
#define rep(i, n) for (int i = 0; i < (int)(n); i++)
int main(){
  string N;
  cin >> N;
  int ans=0;
  rep(i,9){
    if(  (N[i] == 'Z') && (N[i+1] == 'O') && (N[i+2] == 'N') && (N[i+3] == 'e') )ans++;
  }
  cout << ans << endl;
}