n, d = map(lambda s_: int(s_), input().split())
a = tuple(map(lambda s_: int(s_), input().split()))
from collections import defaultdict
mo = defaultdict(list)
for ai in a:
    q, r = divmod(ai, d)
    mo[r].append(q)
ans = 0
for l in mo.values():
    lc = defaultdict(int)
    rc = defaultdict(int)
    for e in l:
        rc[e] += 1
    for me in l:
        rc[me] -= 1
        ans += lc[me - 1] * rc[me + 1]
        lc[me] += 1
print(ans)