#include<iostream>
#include<algorithm>
#include<vector>
#include<queue>
#define lol(i,n) for(int i=0;i<n;i++)
#define mod 1000000007
typedef long long ll;
using namespace std;
int cnt[100010],mcnt[100010],n,m;
int main(){
    lol(i,100010)cnt[i]=0;
    cin>>n>>m;
    lol(i,n){
	int x;cin>>x;
	cnt[x]++;
	mcnt[x%m]++;
    }
    lol(i,100010){
	if(i<m)cnt[i]/=2;
	else cnt[i%m]+=cnt[i]/2;
    }
    int ans=mcnt[0]/2;
    for(int i=1;i<m;i++){
	int to=m-i;
	if(i>to)break;
	if(i==to){
	    ans+=mcnt[i]/2;
	    break;
	}
	if(mcnt[i]<mcnt[to]){
	    ans+=mcnt[i]+min((mcnt[to]-mcnt[i])/2,cnt[to]);
	}
	else{
	    ans+=mcnt[to]+min((mcnt[i]-mcnt[to])/2,cnt[i]);
	}
    }
    cout<<ans<<endl;
    //lol(i,m)cout<<cnt[i]<<" "<<mcnt[i]<<endl;
    return 0;
}
