import java.util.*
import java.math.BigInteger

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

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

	var m = BigInteger.ZERO
	var sum = BigInteger.ZERO
	while (m < n) {
		sum += cin.nextBigInteger()
		m = m + BigInteger.ONE
	}

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