def solve():
    line1 = input().split(' ')
    n = int(line1[0])
    avg = int(line1[1])
    li = input().split(' ')
    sum = 0
    for num in li:
        sum += int(num)
    correctAvg = sum / n
    if (avg == correctAvg):
        print("YES")
    else:
        print("NO")


solve()