#include <bits/stdc++.h>
using namespace std;
int two(int n)
{
    int flag = 0;
    while(n > 0)
    {
        n -= 2;
        flag++;
    }
    return flag;
}

int three(int n)
{
    int flag2 = 0;
    while(n > 0)
    {
        n -= 3;
        flag2++;
    }
    return flag2;
}
int main()
{
    int n;
    cin >> n;
    int ans = two(n);
    int ans2 = three(n);
    cout << min(ans, ans2) << endl;
}