#include<bits/stdc++.h>
using namespace std;
#define getbit(n, i) (((n) & (1LL << (i))) != 0) 
#define setbit0(n, i) ((n) & (~(1LL << (i)))) 
#define setbit1(n, i) ((n) | (1LL << (i))) 

#define ll long long
template<typename s, typename t> void smax(s &a, const t &b) {if (a<b) a=b;}
template<typename s, typename t> void smin(s &a, const t &b) {if (a>b) a=b;}
char gap = 32;

#define rng_init mt19937 rng(chrono::steady_clock::now().time_since_epoch().count())
#define rng_seed(x) mt19937 rng(x)
#define fill(x, y) memset(x, y, sizeof(x))
#define srt(v) sort(v.begin(), v.end())
#define rsrt(v) sort(v.rbegin(),v.rend())
#define pb push_back
#define lll __int128_t
ll hashPrime = 1610612741;

void solve(){
    int n; cin >> n;
    cout << min((n/2),(n/3)) << endl;
}

signed main(){
    ios_base::sync_with_stdio(false);
    cin.tie(0);
    cout.tie(0);
    solve();
}