#include<iostream>
#include<fstream>
long long min(long long a,long long b)
{
     if (a<=b) return a;
        else return b;
     }
  using namespace std;             
                 ifstream f("factorial.in");
                 ofstream g("factorial.out");

int main()
{
    long long i,nr2=0,nr5=0,n,l;
    f>>n;
    f.close();
               for(i=1;0==0;i++)
              { nr5++;long long aux=i;while(aux%5==0) {nr5++;aux/=5;}
              if (nr5>=n) break;
                  }
                                if(nr5>n) g<<"-1";
                  else g<<min(l,i); 
    g.close();
     }