N,M=map(int,input().split())
A=list(map(int,input().split()))

d=dict()
for i in range(N):
    if A[i] in d.keys():
        d[A[i]]+=1
    else:
        d[A[i]]=1
    
if M%2!=0:
    print(0)
    exit()

ans=0
for i in d.keys():
    if i>=M//2+1:
        continue
    j=i+M//2
    if j in d.keys():
        ans+=d[i]*d[j]*(N-d[i]-d[j])
    
print(ans)