#include<fstream>
using namespace std;
int i,j,n,k,x,p,ok,s;
ifstream f("factorial.in");
ofstream g("factorial.out");
int main()
{
	f>>p;
	if(p==0)
		g<<1;
	else
	{
		for(i=5;i<=5*p;i=i+5)
		{
			x=5;
			while(x<=i)
			{
				k=i/x;
				s=s+k;
				x=x*5;
			}
			if(s==p)
			{
				ok=1;g<<i;
				break;
				
			}
			s=0;
		}
	}
	if(ok==0)
		g<<-1;
	
	return 0;
}