//各aについて、mod M = a, M - aのうち片方しか取れない
#include <iostream>
#include <algorithm>
#include <map>
using namespace std;

int n, m;
int a[100000];
map<int, int> mp;

int main() {
	int i;

	cin >> n >> m;
	for (i = 0; i < n; i++) {
		cin >> a[i];
		a[i] %= m;
		if (mp.find(a[i]) == mp.end()) mp[a[i]] = 0;
		mp[a[i]]++;
	}

	int pair_cnt = 0, single_cnt = 0;
	for (map<int, int>::iterator it = mp.begin(); it != mp.end(); it++) {
		int mod = it->first;
		if (mp.find(m - mod) != mp.end()) {
			pair_cnt += max(mp[mod], mp[m - mod]);
		}
		else {
			single_cnt += mp[mod];
		}
	}

	cout << pair_cnt / 2 + single_cnt << endl;
	return 0;
}