#include<fstream.h>
#include<iostream.h>
int main()
{fstream f("fact.in",ios::in);
 fstream g("fact.out",ios::out);
 int p, n=1, x=0, i, j;
 f>>p;
 for(i=1;i<=n;i++)
   {j=i;
   while (j%5==0)
     {x++;
      j/=5;}
   if (x==p) g<<n;
     else if (x>p) g<<-1;
	    else n++;}
 f.close();
 g.close();
 return 0;
}