#include<bits/stdc++.h>
using namespace std;
///Welcome to Nasif's Code
#define bug printf("bug\n");
#define bug2(var) cout<<#var<<" "<<var<<endl;
#define co(q) cout<<q<<endl;
typedef long long int ll;
typedef unsigned long long int ull;
const int MOD = (int)1e9+7;
const int MAX = 1e6;
#define pi acos(-1)
#define inf 1000000000000000LL
#define FastRead    ios::sync_with_stdio(0); cin.tie(0); cout.tie(0);
int main()
{
    FastRead
    //freopen("output.txt", "w", stdout);
     int n;
     cin>>n;
     cout<<n/3<<endl;

    return 0;
}

#include<bits/stdc++.h>
using namespace std;
main()
{
    ios::sync_with_stdio(0);
    cin.tie(0);
    cout.tie(0);

    long long i,j,k,l,m,n,o,p,q;
    while(cin>>m)
    {
        cout<<m/3<<endl;
    }
    return 0;
}