#include<bits/stdc++.h>
using namespace std;
#define ll long long int 
int main()
{
    ll n;
    cin>>n;
    ll mn=n;
    for(int i=0;i<=n;i++)
    {
        for(int j=0;j<=n;j++)
        {
            if(i*3+j*2==n)
            {
                mn=min(mn,(ll)(i+j));

            }
        }
    }
    cout<<mn<<endl;
}