import java.io.*;
import javax.servlet.*;
import javax.servlet.http.*;

public class Silnia extends HttpServlet {
	private int silnia(int n) {
		if (n == 0) return 1;
		else return n * silnia(n - 1);
	}
    @Override
    public void doGet(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {
		String nstr = request.getParameter("n");
		int n = 0;
		if (nstr != null) n = Integer.parseInt(nstr);
        response.setContentType("text/html");
        PrintWriter out = response.getWriter();
        String message = n + "! = " + silnia(n);
        out.println("<h1>" + message + "</h1>");
    }
}