#include <fstream.h>

unsigned long p,q,n,i,k;
unsigned long v[100];

int main()
{
	ifstream be("fact.in");
	ofstream ki("fact.out");

	be >> p;

	while(q<p)
	{
		v[0]++; q++; n+=5;
		k=0;
		while(v[k]==5) {q++; v[k]=0; v[k+1]++; k++;}
	}

	if (q==p)
	{
		if (p==0) ki << 1;
		else ki << n;
	}
	else
		ki << -1;

	be.close();
	ki.close();
	return 1;
}