#include <cstdlib>
#include <cmath>
#include <climits>
#include <cfloat>
#include <map>
#include <set>
#include <iostream>
#include <string>
#include <vector>
#include <algorithm>
#include <sstream>
#include <complex>
#include <stack>
#include <queue>
#include <cstdio>
#include <cstring>
#include <iterator>
#include <bitset>
#include <unordered_set>
#include <unordered_map>
#include <fstream>
#include <iomanip>
#include <cassert>
//#include <utility>
//#include <memory>
//#include <functional>
//#include <deque>
//#include <cctype>
//#include <ctime>
//#include <numeric>
//#include <list>
//#include <iomanip>

//#if __cplusplus >= 201103L
//#include <array>
//#include <tuple>
//#include <initializer_list>
//#include <forward_list>
//
//#define cauto const auto&
//#else

//#endif

using namespace std;


typedef long long ll;
typedef pair<int,int> pii;
typedef pair<ll,ll> pll;

typedef vector<int> vint;
typedef vector<vector<int> > vvint;
typedef vector<long long> vll, vLL;
typedef vector<vector<long long> > vvll, vvLL;

#define VV(T) vector<vector< T > >

template <class T>
void initvv(vector<vector<T> > &v, int a, int b, const T &t = T()){
    v.assign(a, vector<T>(b, t));
}

template <class F, class T>
void convert(const F &f, T &t){
    stringstream ss;
    ss << f;
    ss >> t;
}

#undef _P
#define _P(...) (void)printf(__VA_ARGS__)
#define reep(i,a,b) for(int i=(a);i<(b);++i)
#define rep(i,n) reep((i),0,(n))
#define ALL(v) (v).begin(),(v).end()
#define PB push_back
#define F first
#define S second
#define mkp make_pair
#define RALL(v) (v).rbegin(),(v).rend()
#define DEBUG
#ifdef DEBUG
#define dump(x)  cout << #x << " = " << (x) << endl;
#define debug(x) cout << #x << " = " << (x) << " (L" << __LINE__ << ")" << " " << __FILE__ << endl;
#else
#define dump(x) 
#define debug(x) 
#endif

#define MOD 1000000007LL
#define EPS 1e-8
#define INF 0x3f3f3f3f
#define INFL 0x3f3f3f3f3f3f3f3fLL
#define maxs(x,y) x=max(x,y)
#define mins(x,y) x=min(x,y)

void mainmain(){
	int n,m;
	cin>>n>>m;
	vint v(n);
	rep(i,n) cin>>v[i];
	vvint vv(m);
	sort(ALL(v));
	int ans = 0;
	rep(i,n){
		vv[v[i]%m].PB(v[i]);
	}
	ans += vv[0].size()/2;
	vint used(m);
	used[0]=1;
	rep(i,m){
		if(used[i]) continue;
		int a = i;
		int b = m-i;
		int aa = 0;
		int bb = 0;
		used[a]=1;
		used[b]=1;
		rep(j,vv[a].size()){
			if(j+1<vv[a].size()){
				if(vv[a][j]==vv[a][j+1]){
					aa+=2;
					j++;
				}
			}
		}
		rep(j,vv[b].size()){
			if(j+1<vv[b].size()){
				if(vv[b][j]==vv[b][j+1]){
					bb+=2;
					j++;
				}
			}
		}
		// dump(a);
		// cout << vv[a].size() << " " << aa << endl;
		// cout << vv[b].size() << " " << bb << endl;
		if(a==b){
			ans += aa/2;
			ans += (vv[a].size()-aa)/2;
			continue;
		}
		int t = min(vv[a].size()-aa, vv[b].size()-bb);
		ans += t;
		int ca = vv[a].size()-aa-t;
		int cb = vv[b].size()-bb-t;
		// cout << "cc "<<ca<<" "<<cb<<endl;
		// cout <<ans<<endl;
		assert(ca==0||cb==0);
		if(ca){
			int t = min(bb, ca);
			bb -= t;
			ans += t;
		}
		if(cb){
			int t = min(aa, cb);
			aa -= t;
			ans += t;
		}
		ans += aa/2+bb/2;
	}
	cout<<ans<<endl;
}


signed main() {
    ios_base::sync_with_stdio(false);
    cin.tie(0);
    cout<<fixed<<setprecision(20);
    mainmain();
}

Measured memory_bytes: 6528