<?php
list($n,$a) = explode(" ",trim(fgets(STDIN)));
$N = $n * $a;
$x = explode(" ",trim(fgets(STDIN)));
$i = 0;
while($i < $n){
$N -= $x[$i];
if($N < 0){
echo "NO";
break;
}
++$i;
}

if($N == 0){
echo "YES";
}elseif($N > 0){
echo "NO";
}
?>