#include <iostream>
#include <fstream>

using namespace std;

int main () {

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

int n, i, count, temp;

in >> n;
count = 0;
for (i = 1; i; ++i)
{
	temp = i;
	while (temp % 5 == 0)
	{
		temp /= 5;
		count ++;
	}
	if (count == n)
	{
		out << i;
		break;
	}
}
return 0;
}