#include <fstream>
using namespace std;

ifstream in("fact.in");
ofstream out("fact.out");

int v[1001];
const int L=28;
int n,p;
int nr_zero(int n)
{
    int nr=0;
    while (n>=5)
    {
        nr+=n/5;
        n/=5;
    }
    return nr;
}

int main()
{
   in>>p;
   //caut binar cel mai mare n cu propietatea ca nr_zero(n)<p
   int r=0,pas=1<<L;
   while (pas!=0)
   {
       if (nr_zero(r+pas)<p)
       {
           r+=pas;
       }
       pas/=2;
   }
   r++;
  if (nr_zero(r)>p)
  {
      r=-1;
  }
  out<<r;
   return 0;
}