#include<iostream>
#include<fstream>
                 using namespace std;
                 ifstream f("factorial.in");
                 ofstream g("factorial.out");
double func(unsigned long long c)
{
         unsigned long long aux=c, sum=0;
         while(aux!=0)sum+=aux%5;
         return (double)(c-sum)/4;
}
int main()
{
unsigned long long a=0,b=100000000,p;    
    f>>p;
    f.close();
int flag=1;
    do
    {
         unsigned long long c=(a+b)/2;
         if (func(c)==p) {g<<p;flag=0;break;}
         else if (func(c)>p) b=c-1;
              else a=c+1;}
              while(a<=b);
if (flag) g<<"-1";     
   g.close(); 
    }