Shared code

/*
  author: @ankingcodes
  created: 2021-07-14 17:34:45.168337
*/
        
#include<bits/stdc++.h>
#include<algorithm>
#include<ext/pb_ds/assoc_container.hpp>
#include<ext/pb_ds/tree_policy.hpp>

using namespace __gnu_pbds;
using namespace std;
#define ll long long
#define MOD 1000000007

typedef tree<int, null_type, less<int>, rb_tree_tag,
                tree_order_statistics_node_update> PBDS;

typedef tree<pair<int, int>, null_type, less<pair<int, int>>, rb_tree_tag,
                tree_order_statistics_node_update> pairPBDS;

int main(){
  ios_base::sync_with_stdio(false);
  cin.tie(NULL);
  ll n, k; cin>>n>>k;
  vector<ll> a(n);
  for(auto &i: a) cin>>i;
  sort(a.begin(), a.end());
  ll i = 0, j = a.size() - 1;
  ll ans = 0;
  bool mark[n] = {false};
  while (i < j) {
    if (a[i] + a[j] <= k) {
      ans += 1; 
      mark[i] = mark[j] = true;
      i++; j--;
    } else j--;
  }
  for (ll i=0;i<n;i++) {
    ans += (mark[i]==false);
  }
  cout << ans << endl;
  return 0;
}