#coding:utf-8

get = input()
get = get.split(" ")
get = list(map(int,get))
get1 = input()
get1 = get1.split(" ")
get1 = list(map(int,get1))

ans = get[1] #5
sum_list = sum(get1) #15

if((sum_list / get[0]) == ans):
    print("YES")
else:
    print("NO")