#include <fstream>
#include <vector>
#include <algorithm>


using namespace std;

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

int zeros(int nr) {
	int val = 5;
	int cont = 0;
	while (nr / val) {
		cont += nr / val;
		val *= 5;
	}
	return cont;
}

int p;

int main() {

	cin >> p;

	int ans = 0;

	for (int pas = (1 << 20); pas > 0; pas >>= 1) {
		if (zeros(ans + pas) <= p) {
			ans += pas;
		}
	}

	if (zeros(ans) != p) {
		cout << -1 <<'\n';
		return 0;
	}
	if (p == 0) {
		cout << 1 << '\n';
		return 0;
	}
	cout << ans - 4 << '\n';

}