JavaEE, Servlet, Ошибка создания экземпляра класса сервлета,

подскажите, пожалуйста. Начал разбираться с Java EE, однако возникла проблема с созданием сервлета.

Ошибка:

HTTP Status 500 – Internal Server Error
Type Exception Report

Message Ошибка создания экземпляра класса сервлета [classes.FirstServ]

Description The server encountered an unexpected condition that prevented it from fulfilling the request.

Exception

javax.servlet.ServletException: Ошибка создания экземпляра класса сервлета [classes.FirstServ]
    org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:544)
    org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:81)
    org.apache.catalina.valves.AbstractAccessLogValve.invoke(AbstractAccessLogValve.java:698)
    org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:364)
    org.apache.coyote.http11.Http11Processor.service(Http11Processor.java:624)
    org.apache.coyote.AbstractProcessorLight.process(AbstractProcessorLight.java:65)
    org.apache.coyote.AbstractProtocol$ConnectionHandler.process(AbstractProtocol.java:831)
    org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.doRun(NioEndpoint.java:1651)
    org.apache.tomcat.util.net.SocketProcessorBase.run(SocketProcessorBase.java:49)
    java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1149)
    java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:624)
    org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:61)
    java.lang.Thread.run(Thread.java:748)
Root Cause

java.lang.ClassNotFoundException: classes.FirstServ
    org.apache.catalina.loader.WebappClassLoaderBase.loadClass(WebappClassLoaderBase.java:1415)
    org.apache.catalina.loader.WebappClassLoaderBase.loadClass(WebappClassLoaderBase.java:1223)
    org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:544)
    org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:81)
    org.apache.catalina.valves.AbstractAccessLogValve.invoke(AbstractAccessLogValve.java:698)
    org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:364)
    org.apache.coyote.http11.Http11Processor.service(Http11Processor.java:624)
    org.apache.coyote.AbstractProcessorLight.process(AbstractProcessorLight.java:65)
    org.apache.coyote.AbstractProtocol$ConnectionHandler.process(AbstractProtocol.java:831)
    org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.doRun(NioEndpoint.java:1651)
    org.apache.tomcat.util.net.SocketProcessorBase.run(SocketProcessorBase.java:49)
    java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1149)
    java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:624)
    org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:61)
    java.lang.Thread.run(Thread.java:748)
Note The full stack trace of the root cause is available in the server logs.

Код сервлета FirstServ:

package classes;

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

public class FirstServ extends HttpServlet {
    @Override
    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
    PrintWriter printWriter = response.getWriter();
    printWriter.write("Hello world");
    
}

    @Override
    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
    doGet(request, response);
    }
}

Код файла web.xml с маппингом сервлета:

<?xml version="1.0" encoding="UTF-8"?>
<web-app xmlns="http://xmlns.jcp.org/xml/ns/javaee"
         xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
         xsi:schemaLocation="http://xmlns.jcp.org/xml/ns/javaee http://xmlns.jcp.org/xml/ns/javaee/web-app_4_0.xsd"
         version="4.0">

    <servlet>
        <servlet-name>myServlet</servlet-name>
        <servlet-class>classes.FirstServ</servlet-class>
    </servlet>
    
    <servlet-mapping>
        <servlet-name>myServlet</servlet-name>
        <url-pattern>/please</url-pattern>
    </servlet-mapping>
   
</web-app>