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