<?php
  $token = 'f4e9227c1b7d40ed25802215220fe4b70818bba8b8f66710debbd9f1c565216f834375937b0d0c6f12d82'; // Key for group

  $data = json_decode(file_get_contents('php://input'));

  $user_id = $data->object->user_id;

  $request_params = array(
  'message' => "Hello",
  'user_id' => $user_id,
  'access_token' => $token,
  'v' => '5.0'
  );

  $get_params = http_build_query($request_params);

  file_get_contents('https://api.vk.com/method/messages.send?'.$get_params);

  echo'ok'
?>