#include<bits/stdc++.h>

using namespace std;
#define ll long long
#define momen ios_base::sync_with_stdio(0);cin.tie(0);cout.tie(0);
#define endl "\n"
#define ld long double
#define fp(n) for(int i=0;i<n;i++)
#define fp1(n) for(int i=1;i<=n;i++)
#define all(v) v.begin() , v.end()
const int mod = 1e9 + 7, N = 1e6 + 5, M = 8e6 + 5;
const ll LG = 20, inf = 1e9 + 6;


int dx[] = {0, 0, 1, -1};
int dy[] = {1, -1, 0, 0};


void solve(int z) {
    double  n ;
    cin>>n ;
    cout<<n/4 ;
}


int main() {
    momen
    int t = 1;
#ifndef ONLINE_JUDGE
    freopen("input.txt", "r", stdin);
    freopen("output.txt", "w", stdout);
#endif
//    cin >> t;

    for (int i = 1; i <= t; ++i) {
        //cout<<"Case #"<<i<<": ";
        solve(t);
    }

    return 0;
}