a = input().split()
b = input().split()
n = int(a[0])
c = int(a[1])
d = 0#计数器
e = 0
for i in range(n):
    f = str(c + int(b[e]))
    g = b.count(f)
    d = d + g
    e += 1

print(d)

2,3,4超时