#include <fstream>
using namespace std;
int p;
void citire ()
{
    ifstream in ("fact.in");
    in >> p;
    in.close ();
}
void afis (int rez)
{
    ofstream out ("fact.out");
    out << rez;
    out.close ();
}
void search ()
{
    int st = 1, dr = p * 5, mij, n;
    while (st <= dr)
    {
        mij = (st + dr) / 2;
        n = p % 5;
        if (n == 0)
            n = 5;
        if (mij == p*4 + n)
            {
                afis (mij);
                break;
            }
        else
            if (p * 4 + n < mij)
                dr = mij - 1;
        else
            st = mij + 1;
    }
}
int main()
{
    citire ();
    if (p == p / 5 * 5 + (p / 5 - 1))
        afis (-1);
    else
        if (p == 0)
        afis (1);
    else
        search ();
    return 0;
}