n,c=list(map(int,input().split()))
dl=list(map(int,input().split()))
dc={}
dlrd=[]
for i1 in sorted(dl):
    if not i1 in dc:
        dc[i1]=1
        dlrd.append(i1)
    else:
        dc[i1]+=1
ans=0
for a in dlrd:
    if ((a-c) in dlrd):
        ans+=dc[a]*dc[a-c]
print(ans)