#include<bits/stdc++.h>
using namespace std;
using ll = long long;

void solve() {
     
    int n;
    cin >> n;

    int cnt = 0;
    while (n > 0) {
    	while (n - 3 >= 0) {
    		n -= 3;
    		cnt++;
    	}

    	while (n - 2 >= 0) {
    		n -= 2;
    		cnt++;
    	}
    }

    cout << cnt << '\n';
}

int32_t main() {
	ios_base::sync_with_stdio(false);
    cin.tie(0);

    int tc = 1;
    //cin >> tc;

    while(tc--) {
    	solve();
    }

    return 0;

}