#include <fstream>   
using namespace std;   
ifstream f1 ("fact.in");   
ofstream f2 ("fact.out");   
int main()      
{    
long n,p,i,s,f,m;
f1>>p;   
f1.close(); 
if (p>0)
  {f=0;
   i=p;
   while (i>=p-(p/5))
     {n=5*i;
      s=0;
      m=n; 
      while (m!=0) {m=m/5; s=s+m;}
      if (s==p)
	 {f2<<n; f=1;}
      i--;
     }
     if (f==0) f2<<"-1";
   }
  else f2<<"1"; f2.close();      
}