#include <iostream>
#include <vector>
#include <string>
#include <queue>
#include <fstream>
#include <cmath>

#ifdef PROIECT_LOCAL
	#define NUME "date"
#else
	#define NUME "fact"
#endif

using namespace std;
string fileName = NUME;
ifstream fin(fileName + ".in");
ofstream fout(fileName + ".out");


int main()
{
	int p, n, tmp;
	int put2 = 0, put5 = 0;
	fin >> p;

	for (n = 2; put2 < p || put5 < p; n++)
	{
		tmp = n;
		while (tmp % 2 == 0)
		{
			put2++;
			tmp /= 2;
		}
		while (tmp % 5 == 0)
		{
			put5++;
			tmp /= 5;
		}
	}
	if ((put2 == p || put5 == p) && (put2 >= p && put5 >= p))
		fout << --n;
	else
		fout << -1;
}