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