Implementation in Python

n, k = map(int,raw_input().strip().split(" "))

arr = map(int,raw_input().strip().split(" "))

d = {x:[] for x in range(k)}

for i in range(n): d[arr[i]%k].append(arr[i])

count = 0

if len(d[0]) > 0:

count = 1

S = set([(x,k-x) for x in range(1,k//2+1)])

for i,j in S:

if i != j:

    if len(d[i]) > len(d[j]):

        count += len(d[i])

    else:

        count += len(d[j])

else:

    if len(d[i]) > 0:

        count += 1

print count