# 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()