#include <fstream>;
using namespace std;
int main()
{unsigned p,i,c,b,x;
int d;
ifstream f("fact.in");
ofstream h("fact.out");
f>>p;
if (p==0)
d=1;
else {
c=0;d=0;
i=1;
do
    {d=i*5;
     c=c+1;
     x=0;b=i;
     while(b%5==0)
      {x=x+1;
      b=b/5;
      }
    c=c+x;
    i=i+1;
    }
while(c<p);
if (c>p)
d=-1;}
h<<d<<"\n";
f.close();
h.close();
return 0;}