#include <iostream>
#include <vector>
#include <string>
#include <algorithm>
#include <cmath>
#include <tuple>
#include <bitset>

#define rep(i,n) for(i=0; i<n; ++i)
#define in(a) cin >> a
#define out(a,b) cout << a << b
using namespace std;
using lint = long long;

lint count_elem_inc(vector<lint> x, lint elem, lint *i){
    lint cnt=0;
    for(; *i<x.size(); ++*i){
        if(x[*i]!=elem)  break;
        cnt++;
    }
    return cnt;
}
lint count_elem_dec(vector<lint> x, lint elem, lint *i){
    lint cnt=0;
    for(; *i>0; --*i){
        if(x[*i]!=elem)  break;
        cnt++;
    }
    return cnt;
}

int main(void){
    lint i, j;
    lint p, n, m, cnt=0;
    in(n); in(m);
    vector<lint> rem(n);
    rep(i,n){
        lint input;
        in(input);
        rem[i]=input%m;
    }
    sort(rem.begin(),rem.end());
    lint *cur_l, *cur_r;
    lint init_l=0, init_r=n-1;
    cur_l=&init_l; cur_r=&init_r;
    for(i=1; i<m/2+m%2; ++i){
        for(; rem[*cur_l]<i; ++*cur_l);
        for(; rem[*cur_r]>m-i; --*cur_r);
        lint l_cnt=count_elem_inc(rem, i, cur_l);
        lint r_cnt=count_elem_dec(rem, m-i, cur_r);
        cnt+=max(l_cnt,r_cnt);
    }
    if(m%2==0&&rem[*cur_l]==m/2)  cnt++;
    if(rem[0]==0)    cnt++;
    if(cnt==0)  cnt=1;
    out(cnt,endl);

    return 0;
}