#include <bits/stdc++.h>
using namespace std;
typedef long long int ll;
const ll mod=1e9+7;
ll rn[2000000];
mt19937 akil(chrono::steady_clock::now().time_since_epoch().count());
/*ll my_rand(int l, int r)
{
    return uniform_int_distribution<ll>(l, r) (akil);
}*/

void sufi() {
  ll n;
  cin>>n;
  if(n<=3){
    cout<<"1"<<endl;
    return;
  }
  if(n%3==0){
    cout<<n/3<<endl;
    return;
  }

     cout<<n/3+1<<endl;
    return;

}

int main() {
  //for(int i=0;i<2000000;i++)rn[i]=my_rand(1,1e17);
    int t = 1;
    //cin>>t;
    while (t--) {
        sufi();
    }
}