Cannot GET /api/v1/ , MongoDb

I am trying to test if my serving is working on post man. I tried pasting this http://localhost:80/api/v1/

and i got, Cannot GET /api/v1/

On my terminal on vs code, it looks like the server is running because it showsLISTENING TO PORT: 80 db connected.

here is my code

env file:

PORT=80MONGO_URL =myurl

routes/transaction.js:

const express = require('express');const router = express.Router();router.get('/', (req, res) => {  res.send('Hello, world!');});module.exports = router;

index.js:

const express = require('express')const cors= require('cors')const { db } = require('./db/db')const {readdirSync} = require('fs')const app = express()require('dotenv').config()const PORT =  process.env.PORT//midwares//data is in jsonapp.use(express.json())app.use(cors())//routesreaddirSync('./routes').map((route)=> app.use('/api/v1',require('./routes/'+ route)))const server = ()=>{    db()    app.listen(PORT,()=>{        console.log('LISTENING TO PORT:',PORT);    })}server()

I am using atlas, but I have also tried using mongoDB compass and i still get the same error