from bisect import bisect_left

n, m = map(int, input().split())
A = list(map(int, input().split()))

if m % 2 == 1:
    print(0)
    exit()
A.sort()
A2 = [A[i] + m for i in range(n)]
A = A + A2
ans = 0
for i in range(n):
    a = A[i]
    idx = bisect_left(A, a + m // 2)
    if A[idx] == a + m // 2:
        ans += n - 2
print(ans // 2)