#include<fstream>
using namespace std;
int main()
{long a,p=0,n,i,pb=0,j;
ifstream f("fact.in");
ofstream g("fact.out");
f>>p;
pb=1;
i=5;
while(pb<p)
{;
j=i;
if(j%5==0)
{pb=pb+1;
j=j/5;}
if(j%5==0)
{pb=pb+1;
j=j/5;}
if(j%5==0)
{pb=pb+1;
j=j/5;}
if(j%5==0)
{pb=pb+1;
j=j/5;}
if(j%5==0)
{pb=pb+1;
j=j/5;}
if(j%5==0)
{pb=pb+1;
j=j/5;}
if(j%5==0)
{pb=pb+1;
j=j/5;}
if(j%5==0)
{pb=pb+1;
j=j/5;}
if(j%5==0)
{pb=pb+1;
j=j/5;}
if(j%5==0)
{pb=pb+1;
j=j/5;}
if(j%5==0)
{pb=pb+1;
j=j/5;}
if(j%5==0)
{pb=pb+1;
j=j/5;}
if(j%5==0)
{pb=pb+1;
j=j/5;}
if(j%5==0)
{pb=pb+1;
j=j/5;}
if(j%5==0)
{pb=pb+1;
j=j/5;}
if(j%5==0)
{pb=pb+1;
j=j/5;}
if(j%5==0)
{pb=pb+1;
j=j/5;}
if(j%5==0)
{pb=pb+1;
j=j/5;}
if(j%5==0)
{pb=pb+1;
j=j/5;}
if(j%5==0)
{pb=pb+1;
j=j/5;}
if(j%5==0)
{pb=pb+1;
j=j/5;}
if(j%5==0)
{pb=pb+1;
j=j/5;}
i=i+5;}
if(pb==p)
g<<i;
else
g<<-1;
f.close();
g.close();
return 0;}