#include <fstream>

using namespace std;

int main()
{
    ifstream is("fact.in");
    ofstream os("fact.out");

    unsigned noz, fact(0);

    is >> noz;

    if(noz == 0)
        fact = 1;
    else
    {
        while (noz != 0)
        {
            fact += 5;

            if((fact / 5) % 5 == 0)
            {
                unsigned aux = fact / 5;
                while (aux % 5 == 0)
                {
                    noz --;
                    aux /= 5;
                }
            }

            noz--;
        }
    }

    os << fact;

    os.close();
    is.close();

    return 0;
}