#include <fstream>

using namespace std;

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

int nr0(int k)
{
    int db = 0;
    int ot = 1;

    while (ot <= k)
    {
        db += k / ot;
        ot *= 5;
    }
    return db;
}

int keres(int p, int k, int v)
{
    if (v < k) return -1;

    int kozep = (k + v) / 2;

    int nrkoz = nr0(kozep);
    if (nrkoz == p) return kozep * 5;
    else if (nrkoz < p) return keres(p, kozep + 1, v);
    else return keres(p, k, kozep - 1);
}

int main()
{
    int p;
    cin >> p;
    if (p == 0) cout << "1\n";
    else cout << keres(p, 1, p) << "\n";
}