<?php

// No.476
$args = explode(" ", trim(fgets(STDIN)));
$n = $args[0];
$a = $args[1];

$args = explode(" ", trim(fgets(STDIN)));
$sum = 0;
foreach ($args as $key => $value) {
  $sum += $value;
}
if (($n * $a) == $sum) {
  echo "YES".PHP_EOL;
}
else {
  echo "NO".PHP_EOL;
}
return;