# import sys; input = sys.stdin.buffer.readline
# sys.setrecursionlimit(10**7)
from collections import defaultdict
con = 10 ** 9 + 7; INF = float("inf")

def getlist():
	return list(map(int, input().split()))

#処理内容
def main():
	N, A = getlist()
	X = getlist()
	Xsum = sum(X)
	if N * A == Xsum:
		print("YES")
	else:
		print("NO")



if __name__ == '__main__':
	main()