<?php
define('HOST','84.200.122.139');
define('USER','root');
define('PASS','admin');
define('DB','users');

$con = mysqli_connect(HOST,USER,PASS,DB);

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

$sql = "select * from users where username='$username' and password='$password'";

$res = mysqli_query($con,$sql);

$check = mysqli_fetch_array($res);

if(isset($check)){
echo 'success';
}else{
echo 'failure';
}

mysqli_close($con);
?>