require "set"

N, M = gets.split.map(&:to_i)
A = gets.split.map { _1.to_i % M }

count = Hash.new(0)
A.each do |x|
    count[x] += 1
end

ans = 0
A.map { |x| [x, M - x].min }.uniq.each do |x|
    if x * 2 == M
        ans += 1
    else
        ans += [count[x], count[-x % M]].max
    end
end

puts ans