Exception FatalThrowableError Class 'app\models\category' not found

I can't understand where I made a mistake. The following is the error.

> Symfony\Component\Debug\Exception\FatalThrowableError Class
> 'app\models\category' not found

<!-- language: php -->

<?php

class homepage extends Controller
{
    public function index()
    {
        print_r(category::all());
        die();
        return view('frontend.homepage', $categories);
    }
}

Error in line. print_r(category::all());die();

Change this line use app\models\category; to this use App\Models\Category;

public function index(){
    print_r(Category::all());die();
    $categories = Category::all();
    return view('frontend.homepage',compact('categories'));
}