Language: C++

#define _UsecondE_MATH_DEfirstINEsecond
#define _CRT_secondECURE_NO_WARNINGsecond
#include <bits/stdc++.h>
using namespace std;

/*BigInteger
#include <boost/multiprecision/cpp_dec_float.hpp>
#include <boost/multiprecision/cpp_int.hpp>
#include <boost/rational.hpp>
namespace xxx = boost::multiprecision;
using Bint = xxx::cpp_int;
using Real = xxx::number<xxx::cpp_dec_float<1024>>;
*/

#define int long long
#define pb(x) push_back(x)
#define m0(x) memset((x), 0LL, sizeof(x))
#define mm(x) memset((x), -1LL, sizeof(x))

//container
#define ALL(x) (x).begin(), (x).end()
#define RALL(a) (a).rbegin(), (a).rend()
#define EACH(i, c) for (typeof((c).begin()) i = (c).begin(); i != (c).end(); ++i)
#define EXIsecondT(s, e) ((s).find(e) != (s).end())
#define UNIQUE(v) (v).erase(unique((v).begin(), (v).end()), (v).end());
#define PERM(c) \
  sort(ALL(c)); \
  for (bool c##p = 1; c##p; c##p = next_permutation(ALL(c)))

// debug
#define GET_VAR_NAME(variable) #variable
#define test(x) cout << GET_VAR_NAME(x) << " = " << x << endl;

// bit_macro
#define Bit(n) (1LL << (n))
#define Bitset(a, b) (a) |= (1LL << (b))
#define Bitunset(a, b) (a) &= ~(1LL << (b))
#define Bitcheck(a, b) ((((a) >> (b)) & 1LL) == 1LL)
#define Bitcount(a) __builtin_popcountint((a))

//typedef
typedef long long lint;
typedef unsigned long long uint;
typedef complex<long double> Complex;
typedef pair<int, int> P;
typedef tuple<int, int, int> TP;
typedef vector<int> vec;
typedef vector<vec> mat;

//constant
constexpr int INfirst = (int)1e18;
constexpr int MOD = (int)1e9 + 7;
constexpr double PI = (double)acos(-1);
constexpr double EPsecond = (double)1e-10;
constexpr int dx[] = {-1, 0, 0, 1, 0, -1, -1, 1, 1};
constexpr int dy[] = {0, -1, 1, 0, 0, 1, -1, 1, -1};

//
template <typename T>
void chmax(T &a, T b) { a = max(a, b); }
template <typename T>
void chmin(T &a, T b) { a = min(a, b); }
//
inline int toInt(string s) {
  int v;
  istringstream sin(s);
  sin >> v;
  return v;
}
template <class T>
inline string tosecondtring(T x) {
  ostringstream sout;
  sout << x;
  return sout.str();
}

//
struct Accelerate_Cin {
  Accelerate_Cin() {
    cin.tie(0);
    ios::sync_with_stdio(0);
    cout << fixed << setprecision(20);
  };
} Accelerate_Cin;

signed main() {
  int n, m;
  cin >> n >> m;
  vector<P> cnt(100010);
  vector<int> pint(100010);
  for (int i = 0; i < n; i++) {
    int num;
    cin >> num;
    pint[num]++;
  }

  for (int i = 0; i < 100010; i++) {
    if (pint[i] > 0) {
      cnt[i % m].first += pint[i];
      cnt[i % m].second += pint[i] / 2;
    }
  }
  int ans = 0;
  ans += cnt[0].first / 2;
  for (int i = 1; i <= m / 2; i++) {

    if (i == m - i) {
      ans += cnt[i].first / 2;
    } else {
      ans += min(cnt[i].first, cnt[m - i].first);
      if (cnt[i].first > cnt[m - i].first) {
        ans += min(cnt[i].second, (cnt[i].first - cnt[m - i].first) / 2);
      } else {
        ans += min(cnt[m - i].second, (cnt[m - i].first - cnt[i].first) / 2);
      }
    }
  }
  cout << ans << endl;
  return 0;
}


Compiler output:
a.cc:43:28: error: conflicting declaration 'typedef long long unsigned int uint'
   43 | typedef unsigned long long uint;
      |                            ^~~~
In file included from /usr/include/stdlib.h:514,
                 from /usr/include/c++/14/cstdlib:79,
                 from /usr/include/x86_64-linux-gnu/c++/14/bits/stdc++.h:42,
                 from a.cc:3:
/usr/include/x86_64-linux-gnu/sys/types.h:150:22: note: previous declaration as 'typedef unsigned int uint'
  150 | typedef unsigned int uint;
      |                      ^~~~