#include <fstream>
#include <math.h>
using namespace std;
ifstream f("fact.in");
ofstream g("fact.out");
double cinci=5,c[14]={0,1,6,31,156,781,3906,19531,97656,488281,2441406,12207031,61035156,305175781};
long n;
int c_b(int l,int h)
{
 if (h-l<2)
  return 0;
 int mid=(l+h)/2,x=mid;
 long nr=0;
 while (x>0)
 {
  nr+=x/5;
  x/=5;
 }
 int ok=0;
 while (nr==n)
 {
  ok=1;
  mid--;
  nr=0;
  x=mid;
  while (x>0)
  {
   nr+=x/5;
   x/=5;
  }
 }
 if (ok)
 {
  g<<(mid+1)<<"\n";
  return 1;
 }
 if (nr>n)
  c_b(l,mid);
 else
  c_b(mid,h);
}
int main()
{
 f>>n;
 if (n==0)
  g<<1<<"\n";
 else
 {
  int i=0;
  while (n>c[i])
   i++;
  if (n==c[i])
  {
   double y=i;
   g<<pow(cinci,y)<<"\n";
  }
  else
   if (!c_b(pow(cinci,i-1),pow(cinci,i)))
    g<<"-1\n";
 }
 return 0;
}