using namespace std;
#include<fstream>
#include<math.h>
int main(){
	ifstream f("fact.in");
	ofstream g("fact.out");
	long long a, c, p, b, r;
	f>>p;
	a=4*p+1;
	b=floor(a/5);
	c=a-5*b;
	if (c!=0) a=a+5-c;
	c=5;
	r=0;
	while (c<=a){
		r=r+floor(a/c);
		c=c*5;
	}
	if (r!=p) g<<"-1";
	else 
	g<<a;
	return 0;
}