#include<fstream>
using namespace std;
ifstream f("fact.in");
ofstream g("fact.out");
long long pt;
int n,p,u,m,k,nr;
int main(){
    f>>k;
    p=1;
    u=2000000000;
    if(k==0)
    {
        g<<1;
        return 0;
    }
    while(p<=u){
        m=(p+u)/2;
        pt=5;// puteri ale lui 5
        nr=0;// nr de zerouri ale lui m!
        while(pt<=m){
            nr=nr+m/pt;
            pt=pt*5;
          }
       if(nr==k){
         while(m%5!=0)
          m--;
          g<<m;
          break;
        }
        else
         if(nr<k)
            p=m+1;
          else
          u=m-1;

    }
    if(p>u)
       g<<-1;


return 0;

}