#include <iostream>
#include <fstream>
#include <stdlib.h>
#include <time.h>

using namespace std;

ifstream fin("fact.in");
ofstream fout("fact.out");

int makeMultiple(int x) {
	int c = x % 10;
	if (c >= 5)
		c -= 5;
	x -= c;
	return x;
}

int no_of_zero(int x) {
	
	int nr = 0;
	for (int p = 5;p <= x;p *= 5) {
		nr += x / p;
	}
	return nr;
}

int solve(int a, int b, int p) {

	while (a <= b) {
		int m = (a + b) / 2;
		int nr = no_of_zero(m);
		if (nr == p)
			return makeMultiple(m);
		if (nr < p)
			a = m + 1;
		else
			b = m - 1;
	}
	return -1;
}


int main()
{
	int p;
	fin >> p;
	if (p == 0)
		fout << 1;
	else
		fout << solve(5, 5 * p, p);

	return 0;
}