package main

import "fmt"

func main() {
	var n, a, t, x int
	fmt.Scan(&n, &a)

	for i := 0; i < n; i++ {
		fmt.Scan(&t)
		x += t
	}

	if float64(x)/float64(n) == float64(a) {
		fmt.Println("YES")
	} else {
		fmt.Println("NO")
	}
}