from collections import defaultdict

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

A=list(map(int,input().split()))
D=defaultdict(int)

for a in A:
    D[a%M]+=1

X=0
K=list(D.keys())
for a in K:
    b=(M-a)%M
    X+=max(D[a],D[b])
    D[a]=D[b]=0

print(X)