#include<fstream.h>
#include<math.h>

unsigned long p,n,e,i,d,c,ok;

void citire();
void prel();
void afis();

void citire()
{  ifstream fin("fact.in");
   fin>>p;
   fin.close();
}

void prel()
{  if(p==0) n=1;
   c=1;
   ok=0;
   for(i=1;i<=c&&ok;i++)
   {    d=i;
       while(d%5==0)
       { d/=5;
	e++;
       }
       if(e==p)
		{ n=i;
		  break;
		}
	c++;
   }
}

void afis()
{  ofstream fout("fact.out");
   if(ok)fout<<n;
      else fout<<-1;
   fout.close();
}

int main()
{  citire();
   prel();
   afis();
   return 0;
}