//www.infoarena.ro/problema/fact

#include <fstream>
#include <iostream>
using namespace std;

int p;
long long n = 0, n_u;

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

int main(){
	in >> p;
	
	if (p == 0){
		out << 1;
		return 0;
	}

	while (p > 0){
		n += 5;
		n_u = n;
		while (n_u % 5 == 0){
			n_u /= 5;
			p--;
		}

	}
	out << n;
	return 0;
}