#include <iostream>
#include <fstream>
#include <cstring>
#include <cmath>
#include <algorithm>
#include <string>
#include <sstream>
#include <string.h>
#include <deque>
using namespace std;

ifstream fin("fact.in");
ofstream fout("fact.out");
int p, x = 1, cop, j=0;

int fract(int i) {

	x = i * 5 - j*5;
	cop = x;
	while ((cop/5)%5==0&&cop/5!=1) {
		cop /= 5;
		if (i == p) return -1;
		
		j++;i++;
	}
	
	//cout << x << " " << i <<" " << j << '\n';
	if (p == i) return x;
	fract(i + 1);

}

int main() {
	fin >> p;
	if (p == 0) fout << 1;
	else fout << fract(1);
}