#include<fstream>
#define InFile "fact.in"
#define OutFile "fact.out"
using namespace std;
long long p;
unsigned long long nr;
unsigned short v[1000],i;
int main()
{
    ifstream fin(InFile);
    ofstream fout(OutFile);
    fin>>p;
    do
   {
     nr+=5;v[1]++;i=1;--p;
      while(v[i])
       if(v[i]==5){v[i]=0;v[++i]++;--p;}else break;

    }while(p>0);

    if(p<0)fout<<-1;
      else fout<<nr;
    return 0;
}