#include <iostream>
using namespace std;
typedef unsigned long long LL;
int main(int argc, char* argv[])
{
	LL N;
	cin>>N;
	LL n=0;
	LL N1=(N*3)/3;
	N1/=3;
	n+=N1;
	N1=(N*5)/5;
	N1/=5;
	n+=N1;
	cout<<2*n<<endl;
	return 0;
}