package main

import (
	"fmt"
)

func main() {
	var n, a int
	fmt.Scan(&n, &a)
	sum := 0
	for i := 0; i < n; i++ {
		var x int
		fmt.Scan(&x)
		sum += x
	}
	ret := a*n == sum
	if ret {
		fmt.Println("YES")
	} else {
		fmt.Println("NO")
	}
}