import java.util.*

fun main(args: Array<String>) {
	val cin = Scanner(System.`in`)

	val n = cin.nextInt()
	val avr = cin.nextInt()

	var m = 0
	var sum = 0
	while (m < n) {
		sum += cin.nextInt()
		m++
	}

	if ((n * avr) == sum) {
		println("YES")
	}
	else {
		println("NO")
	}
}