#include <fstream>
using namespace std;
 int main()
 {   int n,l,m,p;
 ifstream f("fact.in");
ofstream g("fact.out");
f>>p;
l=p;
n=0;
if(p==0) g<<1;
else if(p==5) g<<-1;
else{while(l!=0) {n=n+5;
                    m=n;
                      while(m%5==0) {l--;
                                      m=m/5;      }     }
                g<<n;

}
return 0;
}