#include <fstream>
using namespace std;
int main()
{
    ifstream in("fact.in");
    ofstream out("fact.out");
    long n=0, p;
    long i, j, r;
    in>>p;
    if(p==0) n=1;
    while(p)
    {
        for(i=1, j=0, r=1; r<=p; i*=5, ++j, r=r*5+1);
        if(r-j<=p&&p<r)
        {
            n=-1;
            break;
        }
        r=(r-1)/5;
        n+=i*(p/r);
        p-=r*(p/r);
    }
    out<<n<<'\n';
    in.close(); out.close();
    return 0;
}