#include<fstream>
using namespace std;
long int p,r;
int main()
{
	ifstream f("fact.in");
	ofstream g("fact.out");
	f>>p;
	if(p==0){g<<1;return 0;}
	if(p%5==0&&p%10!=0){g<<"-1";return 0;}
	r=(p-(p/5)+(p/10))*5;
	g<<r;
	return 0;
}