#include<iostream>
#include<fstream>
using namespace std;
int i,P,aux,k;
int main()
{
    ifstream f("factorial.in");
    ofstream g("factorial.out");

    f>>P;
    if(P==0) {i=1;
              g<<i;}
    else
    {
       i=0;
       k=0;
       while(k<P)
       {
           i=i+5;
           aux=i;
           while(aux%10==0) {aux=aux/10;
                           k++;}
            while (aux%5==0) {aux=aux/5;
                              k++;}

       }
       if(k>P) {i=-1;
       g<<i;}
       else
       g<<i;}






    return 0;


}