#include <fstream>

using namespace std;

ifstream cin ("fact.in");
ofstream cout ("fact.out");

const int L = 28;

int nrzerouri(int n)
{
    int nr = 0;

    while(n >= 5)
    {
        nr += n / 5;
        n /= 5;
    }

    return nr;
}

int caut(int n)
{
    int r, pas;

    pas = 1 << L;

    r = 0;

    while(pas != 0)
    {
        if (nrzerouri (r + pas) < n)
            r += pas;

        pas /= 2;
    }

    r++;
    return r;
}

int main()
{
    int n;
    cin >> n;
    int r = caut(n);

    if(nrzerouri(r) == n)
        cout << r;

    else cout << "-1";

    return 0;

}