import sys
from typing import List, Tuple
from collections import defaultdict


def int1(x: str, /): return int(x) - 1


def input(): return sys.stdin.readline().rstrip('\n')


def dbg(*args, **kwargs):
    print(*(repr(arg) for arg in args), *(f'{k}: {repr(v)}' for k, v in kwargs.items()),
          sep='; ', file=sys.stderr, flush=True)


def main():
    n, d = map(int, input().split())
    *a, = map(int, input().split())
    ll, rr = defaultdict(int), defaultdict(int)
    for v in a:
        rr[v] += 1

    ans = 0
    for v in a:
        rr[v] -= 1
        ans += ll[v - d] * rr[v + d]
        ll[v] += 1
    return ans


def _start():
    ret = main()

    if ret is not None:
        if isinstance(ret, List) or isinstance(ret, Tuple):
            print(*ret)
        else:
            print(ret)


if __name__ == '__main__':
    _start()