from collections import defaultdict
n,m=map(int,input().split())
a=list(map(lambda x : int(x) % m,input().split()))
d=defaultdict(int)
for b in a:
    d[b]+=1
    d[m-b]
ans=0
for k in d.keys():
    ans+=max(d[k],d[m-k])
    d[k]=d[m-k]=0
print(ans)