Cannot GET /to-do.html when I click on button linked (Node js)

I am creating nodeJS app. I am having index.html in which other HTML files (notes.html, to-do.html, etc.) are linked with but these are not working its giving error :

Cannot GET /to-do.html

My other HTML files are simply blank files with little text for now but I will be editing them. The main issue is that I am unable to load these pages, what should I do now.

index.html File :

<nav class="navbar navbar-expand-lg navbar-dark">
    <div class="collapse navbar-collapse" id="nav-dropdown">
      <ul class="navbar-nav ms-right">
        <li class="nav-item">
          <a href="/to-do.html" class="nav-link">To-Do</a>
        </li>
      </ul>
    </div>
</nav>

 

My node.js file

 //jshint esversion: 6

const express = require("express");
const path=require('path');
const https = require('https');

const app = express();

app.use(express.static(path.join(__dirname,"/public")));

app.get("/", function (req, res) {
    res.sendFile(__dirname + "/index.html");
});

app.get("/toDo", function (req, res) {
    res.sendFile(__dirname + "/to-do.html");
});

app.get("/notes", function (req, res) {
    res.sendFile(__dirname + "/notes.html");
});

app.get("/currentAffairs", function (req, res) {
    res.sendFile(__dirname + "/currentAffairs.html");
});

app.listen(3000,function(){
    console.log("Server started on port 3000");
});

Code File screenshot