#include<bits/stdc++.h>
#define iamspeed ios_base::sync_with_stdio(false);cin.tie(NULL);cout.tie(NULL);
#define endl '\n'
using namespace std;
typedef long long int ll;
const ll modd=1e9+7;
const ll N=1e6+5;
ll x,y,z,n,m,k,w,sum,ans,cnt,cnt2,res,mn,mx,t,tt,q,i,j;
string s,ss;
int main()
{
    iamspeed


    cin>>n;
    if(n<=3)
    {
        cout<<1<<endl;
    }
    else if(n<=5)
    {
        cout<<2<<endl;
    }
    else
    {
        cout<<(n/3+(n%3!=0))<<endl;
    }




    return 0;
}