N, M = map(int, input().split())
A = set(map(int, input().split()))
if M % 2:
    print(0)
    exit()
    
ans = 0
for a in A:
    if (a + M // 2)%M in A or (a + M // 2)%M + M in A:
        ans += N - 2
        
print(ans//2)