#include <fstream.h>
#include <math.h>

ifstream f("fact.in");
ofstream g("fact.out");


long n,s,k,li,ls,gasit,n_aux;


int main()
{	f>>k;
	li=0;ls=1000000015;gasit=0;

	while (li!=ls){
		n_aux=n=(li+ls)/2;
		s=0;
		while (n!=0)
		{s+=n/5;
		 n=n/5;
		}
		if (s<k) li=(li+ls)/2+1;
		else if (s>k) ls=(li+ls)/2;
		else {gasit=1;break;}
	}
	if (k==0) g<<1;
	else {
	n_aux=n_aux/5*5;
	if (gasit) g<<n_aux;
	else g<<"-1";}
	f.close();
	g.close();
	return 0;

}