自己看

#include<bits/stdc++.h>
using namespace std;
typedef long long ll;
ll n,ans=0;
int main(){
	//freopen(".in","r",stdin);
	//freopen(".out","w",stdout);
	std::ios::sync_with_stdio(false);
	std::cin.tie(nullptr);
	std::cout.tie(nullptr);
	cin>>n;
	for(ll i=0;i<=n/7;i++){
		ll j=(n-7*i)/4;
		if((n-7*i)%4==0&&(n-i-j)%3==0) ans++;		
    }
	cout<<ans<<endl;
	//fclose(stdin);
	//fclose(stdout);
	return 0;
}
//coder::by::M91