package main

import "fmt"

func main() {
	var n, a, x, t int
	fmt.Scan(&n, &a)
	for i := 0; i < n; i++ {
		fmt.Scan(&x)
		t += x
	}
	if float64(a) == (float64(t) / float64(n)) {
		fmt.Println("YES")
		return
	}
	fmt.Println("NO")
}