#include<fstream>
using namespace std;
ifstream f("fact.in");
ofstream g("fact.out");
int main()
{
	int x,s=0,y=0;
	f>>x;
	if(x==0)g<<1;
	else
	{
	y=x;
	if(x>5)
	{	
	while(x>=5)
	{
		x=x-5;
		s=(int)x/2;
	}
	if((y-s)%5==0)g<<-1;
	else g<<(y-s-1)*5;
	}
	else g<<x*5;
	}
}