login.php

<?php
session_start();

$users = [

    "1" => "1",
    "john" => "pass1",
    "bon" => "pass2",
    "gon" => "pass3"
];

if (isset($_POST['submit'])) {

    $username = $_POST['username'];
    $password = $_POST['password'];

    foreach ($users as $val => $key) {

        if($username == $val && $password == $key) {
            print 'hi';
        } else {
            print 'fuck off';
        }
    }
}
?>