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

ifstream in;
ofstream out;

int main() {
	bool a = true;
	long int P, nr2=0, nr5=0;
	long long int	N=0, n;

	in.open("fact.in");
	in >> P;
	in.close();
	
	while (a)
	{
		N++;
		n = N;
		while (n % 2 == 0)
		{
			nr2++;
			n /= 2;
		}
		while (n % 5 == 0)
		{
			nr5++;
			n /= 5;
		}
		if (min(nr2, nr5) >= P)
		{
			a = false;
		}
	}
	out.open("fact.out");
	out << N;
	out.close();
}