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

    return 0;
}