#include<fstream.h>
int main(){
ifstream fin("fact.in");
ofstream fout("fact.out");
long int  P,nr,x=0,N=0;
fin>>P;
if (P==0)
   fout<<1;
   else
 /*  while (N!=P){
	 x+=5;
	 nr=x;
	while (nr%5==0){
	       nr/=5;
	       N++;}
	  }  */
    N=P*5;
    x=N;
    while (x>0)
       x/=25;
       N-=5;
if (N!=P||P<0)
fout<<-1;
else
fout<<x;
fin.close();
fout.close();
return 0;
}