#include <iostream>
#include <fstream>

using namespace std;

int nrz(int x) {
	int s = 0;
	while (x) {
		s += x / 5;
		x /= 5;
	}
	return s;
}

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

	int p, lo, hi, mid, t;
	f >> p;
	lo = 0;
	hi = 100000000;
	t = -1;

	while (hi - lo > 5 && t != p) {
		mid = 5*((lo + hi) / 10);
		t = nrz(mid);
		if (t < p)
			lo = mid;
		else
			hi = mid;
	}

	if (t == p)
		g << hi;
	else
		g << "-1";

	f.close();
	g.close();
	return 0;
}