import sys
input = sys.stdin.readline

n, m = map(int, input().split())
a = sorted(map(int, input().split()))

if(m & 1):
    exit(print(0))

ans = 0
for x in a:
    def bin_search(x):
        ok = 0
        ng = len(a)
        while(abs(ok - ng) > 1):
            mid = (ok + ng) // 2
            if(a[mid] <= x):
                ok = mid
            else:
                ng = mid
        return (a[ok] == x)
    if not(bin_search(x + m // 2)):
        continue
    ans += n - 2
print(ans)