#include<bits/stdc++.h>
using namespace std;
typedef long long int ll;
#define MOD 1000000007
#define test int t;cin>>t;while(t--)
#define pb push_back
#define vi vector<int>
#define vl vector<ll>
#define F first
#define S second
#define yes cout<<"YES"<<'\n';
#define no cout<<"NO"<<'\n';
#define endl "\n"
#define all(v) v.begin(),v.end()
#define print(v) for(auto it:v) cout<<it<<" "; cout<<endl;
#define srt(v) sort(v.begin(),v.end());
#define rsrt(v) sort(v.rbegin(),v.rend());
#define rvs(v) reverse(v.begin(),v.end());
#define coutv(v) for(auto it:v)cout<<it<<' ';cout<<endl;
#define cinv(v) for(auto &it:v)cin>>it;
#define rall(v) v.rbegin(),v.rend()
#define gcd(a,b) __gcd(a,b)
#define lcm(a,b) (a*b)/gcd(a,b)
#define PI 2*acos(0.0)
#define pr pair<int,int>
#define Tasrik ios_base::sync_with_stdio(0);  cin.tie(0); cout.tie(0);

void abrakadabra()
{
    ll n;
    cin>>n;

    ll x=n/3;
    if(n%3)
        x++;

    cout<<x<<endl;

}

int main ()
{
    Tasrik;
    //test
    abrakadabra();
    return 0;
}