# input
num_ave = input().split()
n = int(num_ave[0])
a = int(num_ave[1])
x_inp = input().split()
x = []
for i in range(n):
    x.append(int(x_inp[i]))

# process
s = sum(x)

if (s/n) == a:
    print('YES')
else:
    print('NO')