n,c = input().split()
d = input().split()
d = list(map(int,d))
c = int(c)
ans = 0
for a in range(len(d)):
    for b in range(len(d)):
        if(a == b):
            continue
        else:
            if(d[a]-d[b] == c):
                ans+=1
print(ans)