#include <iostream>

using namespace std;

int main()
{
    int coins = 0;
    int change[3];
    int suma = 0;

    cin >> coins;

    for(int i=0; i<3; i++)
    {
          change[i] = coins/(i+2);
    }

    for(int i=0; i<3; i++)
    {
          suma += change[i];
    }

    if(suma > coins)
      {
            cout << suma << endl;
      }else{
            cout << coins << endl;
      }

    return 0;
}