#include <iostream>
#include <fstream>

using namespace std;

ifstream f("fact.in");
ofstream g("fact.out");

int main()
{
    long long p,q;
    f>>p;
    if(p==0)
        g<<'1';
    else
    {
        q=p/5;
        q=q*5+q-1;
        if(p==q)
            g<<'-1';
        else {
            if(p%5==0)
                g<<p*5-(p/5-1)*5;
            else g<<p*5-(p/5)*5;}
    }
    f.close();
    g.close();
    return 0;
}