Language: C++

/**
 * @Author: harshkhajuria
 * @Date:   09-May-2020 05:39:30 pm
 * @Email:  khajuriaharsh729@gmail.com
 * @Filename: B - Trick or Treat.cpp
 * @Last modified by:   harshkhajuria
 * @Last modified time: 09-May-2020 05:50:28 pm
 */

#include <bits/stdc++.h>
#define ll long long
#define mp(a, b) make_pair(a, b)
#define newline cout << endl;
#define ff first
#define ss second
#define pii pair<int, int>
#define pll pair<ll, ll>
#define all(v) v.begin(),v.end()
using namespace std;

template <typename S, typename T> ostream& operator<<(ostream& out, pair<S, T> const& p)
{
		out << '(' << p.ff << ", " << p.ss << ')';
		return out;
}

template <typename T> ostream& operator<<(ostream& out, vector<T> const& v)
{
		int l = v.size();
		for (int i = 0; i < l - 1; i++)
				out << v[i] << ' ';
		if (l > 0)
				out << v[l - 1];
		return out;
}

template <typename T> void trace(const char* name, T&& arg1) {
		cout << name << " : " << arg1 << endl;
}

template <typename T, typename ... Args> void trace(const char* names, T&& arg1, Args&&... args)
{
		const char* comma = strchr(names + 1, ',');
		cout.write(names, comma - names) << " : " << arg1 << " | ";
		trace(comma + 1, args ...);
}

/*Input*/
ll n,k;
const ll size = 1e4 + 10;
vector<ll> v(size);
/*Input*/

int main()
{
		//ios::sync_with_stdio(false);
		//cin.tie(0);
		//cout.tie(0);
		clock_t tStart = clock();
		int test;
		test = 1;
		// cin >> test;
		while (test--) {
				cin >> n >> k;
				for(int i=0; i<size; i++) {
						v[i] = 0;
				}
				for(int i=0; i<k; i++) {
						ll x;
						cin >> x;
						for(int j=0; j<x; j++) {
								ll temp2;
								cin >> temp2;
								v[--temp2]++;
						}
				}
				ll ans = 0;
				for(int i=0; i<n; i++) {
						if(v[i] == 0) ans++;
				}
				cout << ans << endl;
		}
#ifdef LOCAL_DEFINE
		printf("Time taken: %.2fs\n", (double)(clock() - tStart) / CLOCKS_PER_SEC);
#endif
		return 0;
}


Compiler output:
a.cc:51:14: error: reference to 'size' is ambiguous
   51 | vector<ll> v(size);
      |              ^~~~
In file included from /usr/include/c++/14/string:53,
                 from /usr/include/c++/14/bitset:52,
                 from /usr/include/x86_64-linux-gnu/c++/14/bits/stdc++.h:52,
                 from a.cc:10:
/usr/include/c++/14/bits/range_access.h:272:5: note: candidates are: 'template<class _Tp, long unsigned int _Nm> constexpr std::size_t std::size(const _Tp (&)[_Nm])'
  272 |     size(const _Tp (&)[_Nm]) noexcept
      |     ^~~~
/usr/include/c++/14/bits/range_access.h:262:5: note:                 'template<class _Container> constexpr decltype (__cont.size()) std::size(const _Container&)'
  262 |     size(const _Container& __cont) noexcept(noexcept(__cont.size()))
      |     ^~~~
a.cc:50:10: note:                 'const long long int size'
   50 | const ll size = 1e4 + 10;
      |          ^~~~
a.cc: In function 'int main()':
a.cc:65:48: error: reference to 'size' is ambiguous
   65 |                                 for(int i=0; i<size; i++) {
      |                                                ^~~~
/usr/include/c++/14/bits/range_access.h:272:5: note: candidates are: 'template<class _Tp, long unsigned int _Nm> constexpr std::size_t std::size(const _Tp (&)[_Nm])'
  272 |     size(const _Tp (&)[_Nm]) noexcept
      |     ^~~~
/usr/include/c++/14/bits/range_access.h:262:5: note:                 'template<class _Container> constexpr decltype (__cont.size()) std::size(const _Container&)'
  262 |     size(const _Container& __cont) noexcept(noexcept(__cont.size()))
      |     ^~~~
a.cc:50:10: note:                 'const long long int size'
   50 | const ll size = 1e4 + 10;
      |          ^~~~