#include<bits/stdc++.h>
#define ll long long
#define el '\n'
#define pb push_back
#define pb1 pop_back
#define swift ios_base::sync_with_stdio(0); cin.tie(nullptr);
#define pr cin.exceptions(ios::badbit | ios::failbit);
using namespace std;


int main() {

    swift;
    pr;

    ll tt=1;
    //cin>>tt;
    while(tt--) {
       ll n;
       cin>>n;
       ll c=0;
       while(n>0){
        if(n%3==0) {
            n-=3;
        } else {
            n-=2;
        }
        c++;
       }
       cout<<c<<el;
    }
    return 0;
}