Language: C++

//#include<bits/stdc++.h> using namespace std;
#include<iostream>
using namespace std;
#include<algorithm>
#include<map>
#include<vector>
#include<set>
#include<stack>
#include<queue> //priority_queue inside queue
#include<deque>
#define fast ios_base::sync_with_stdio(false); cin.tie(NULL); cout.tie(NULL);
#define nl '\n'
typedef long long ll;
typedef unsigned long long ull;
#define f(i,start,end) for(i=start;i<=end;i++)
#define min_heap priority_queue<int, vector<int>, greater<int> >
#define max_heap priority_queue<int>

bool isPrime(int n)
{
    for(int i=2; i*i<=n; i++)
    {
        if(n%i==0) return false;
    }
    return true;
} //returns true if prime!

bool b[200001];
int dp[200001];

int main()
{
    fast;
//int t=0,tc=0; cin >> tc; f(t,1,tc) //testcases
    {
        int n, k; cin >> n >> k;
        bool b[n+1] = {0};
        while(k--)
        {
           int d; cin  >> d;
           while(d--)
           {
              int tmp; cin >> tmp;
              if(b[tmp]==0)
              {
                 n--; b[tmp]=1;
              }
           }
        }
        cout << n < nl;
    }
    return 0;
}
    

Compiler output:
a.cc: In function 'int main()':
a.cc:50:19: error: no match for 'operator<' (operand types are 'std::basic_ostream<char>' and 'char')
   50 |         cout << n < nl;
      |         ~~~~~~~~~ ^
      |              |
      |              std::basic_ostream<char>
a.cc:50:19: note: candidate: 'operator<(int, int)' (built-in)
   50 |         cout << n < nl;
      |                   ^
a.cc:50:19: note:   no known conversion for argument 1 from 'std::basic_ostream<char>' to 'int'
In file included from /usr/include/c++/14/string:48,
                 from /usr/include/c++/14/bits/locale_classes.h:40,
                 from /usr/include/c++/14/bits/ios_base.h:41,
                 from /usr/include/c++/14/ios:44,
                 from /usr/include/c++/14/ostream:40,
                 from /usr/include/c++/14/iostream:41,
                 from a.cc:2:
/usr/include/c++/14/bits/stl_iterator.h:448:5: note: candidate: 'template<class _Iterator> constexpr bool std::operator<(const reverse_iterator<_Iterator>&, const reverse_iterator<_Iterator>&)'
  448 |     operator<(const reverse_iterator<_Iterator>& __x,
      |     ^~~~~~~~
/usr/include/c++/14/bits/stl_iterator.h:448:5: note:   template argument deduction/substitution failed:
a.cc:12:12: note:   'std::basic_ostream<char>' is not derived from 'const std::reverse_iterator<_Iterator>'
   12 | #define nl '\n'
      |            ^~~~
a.cc:50:21: note: in expansion of macro 'nl'
   50 |         cout << n < nl;
      |                     ^~
/usr/include/c++/14/bits/stl_iterator.h:493:5: note: candidate: 'template<class _IteratorL, class _IteratorR> constexpr bool std::operator<(const reverse_iterator<_Iterator>&, const reverse_iterator<_IteratorR>&)'
  493 |     operator<(const reverse_iterator<_IteratorL>& __x,
      |     ^~~~~~~~
/usr/include/c++/14/bits/stl_iterator.h:493:5: note:   template argument deduction/substitution failed:
a.cc:12:12: note:   'std::basic_ostream<char>' is not derived from 'const std::reverse_iterator<_Iterator>'
   12 | #define nl '\n'
      |            ^~~~
a.cc:50:21: note: in expansion of macro 'nl'
   50 |         cout << n < nl;
      |                     ^~
/usr/include/c++/14/bits/stl_iterator.h:1694:5: note: candidate: 'template<class _IteratorL, class _IteratorR> constexpr bool std::operator<(const move_iterator<_IteratorL>&, const move_iterator<_IteratorR>&)'
 1694 |     operator<(const move_iterator<_IteratorL>& __x,
      |     ^~~~~~~~
/usr/include/c++/14/bits/stl_iterator.h:1694:5: note:   template argument deduction/substitution failed:
a.cc:12:12: note:   'std::basic_ostream<char>' is not derived from 'const std::move_iterator<_IteratorL>'
   12 | #define nl '\n'
      |            ^~~~
a.cc:50:21: note: in expansion of macro 'nl'
   50 |         cout << n < nl;
      |                     ^~
/usr/include/c++/14/bits/stl_iterator.h:1760:5: note: candidate: 'template<class _Iterator> constexpr bool std::operator<(const move_iterator<_IteratorL>&, const move_iterator<_IteratorL>&)'
 1760 |     operator<(const move_iterator<_Iterator>& __x,
      |     ^~~~~~~~
/usr/include/c++/14/bits/stl_iterator.h:1760:5: note:   template argument deduction/substitution failed:
a.cc:12:12: note:   'std::basic_ostream<char>' is not derived from 'const std::move_iterator<_IteratorL>'
   12 | #define nl '\n'
      |            ^~~~
a.cc:50:21: note: in expansion of macro 'nl'
   50 |         cout << n < nl;
      |                     ^~
In file included from /usr/include/c++/14/bits/stl_algobase.h:64,
                 from /usr/include/c++/14/string:51:
/usr/include/c++/14/bits/stl_pair.h:1045:5: note: candidate: 'template<class _T1, class _T2> constexpr bool std::operator<(const pair<_T1, _T2>&, const pair<_T1, _T2>&)'
 1045 |     operator<(const pair<_T1, _T2>& __x, const pair<_T1, _T2>& __y)
      |     ^~~~~~~~
/usr/include/c++/14/bits/stl_pair.h:1045:5: note:   template argument deduction/substitution failed:
a.cc:12:12: note:   'std::basic_ostream<char>' is not derived from 'const std::pair<_T1, _T2>'
   12 | #define nl '\n'
      |            ^~~~
a.cc:50:21: note: in expansion of macro 'nl'
   50 |         cout << n < nl;
      |                     ^~
In file included from /usr/include/c++/14/bits/basic_string.h:47,
                 from /usr/include/c++/14/string:54:
/usr/include/c++/14/string_view:673:5: note: candidate: 'template<class _CharT, class _Traits> constexpr bool std::operator<(basic_string_view<_CharT, _Traits>, basic_string_view<_CharT, _Traits>)'
  673 |     operator< (basic_string_view<_CharT, _Traits> __x,
      |     ^~~~~~~~
/usr/include/c++/14/string_view:673:5: note:   template argument deduction/substitution failed:
a.cc:12:12: note:   'std::basic_ostream<char>' is not derived from 'std::basic_string_view<_CharT, _Traits>'
   12 | #define nl '\n'
      |            ^~~~
a.cc:50:21: note: in expansion of macro 'nl'
   50 |         cout << n < nl;
      |                     ^~
/usr/include/c++/14/string_view:680:5: note: candidate: 'template<class _CharT, class _Traits> constexpr bool std::operator<(basic_string_view<_CharT, _Traits>, __type_identity_t<basic_string_view<_CharT, _Traits> >)'
  680 |     operator< (basic_string_view<_CharT, _Traits> __x,
      |     ^~~~~~~~
/usr/include/c++/14/string_view:680:5: note:   template argument deduction/substitution failed:
a.cc:12:12: note:   'std::basic_ostream<char>' is not derived from 'std::basic_string_view<_CharT, _Traits>'
   12 | #define nl '\n'
      |            ^~~~
a.cc:50:21: note: in expansion of macro 'nl'
   50 |         cout << n < nl;
      |                     ^~
/usr/include/c++/14/string_view:688:5: note: candidate: 'template<class _CharT, class _Traits> constexpr bool std::operator<(__type_identity_t<basic_string_view<_CharT, _Traits> >, basic_string_view<_CharT, _Traits>)'
  688 |     operator< (__type_identity_t<basic_string_view<_CharT, _Traits>> __x,
      |     ^~~~~~~~
/usr/include/c++/14/string_view:688:5: note:   template argument deduction/substitution failed:
a.cc:12:12: note:   mismatched types 'std::basic_string_view<_CharT, _Traits>' and 'char'
   12 | #define nl '\n'
      |            ^~~~
a.cc:50:21: note: in expansion of macro 'nl'
   50 |         cout << n < nl;
      |                     ^~
/usr/include/c++/14/bits/basic_string.h:3874:5: note: candidate: 'template<class _CharT, class _Traits, class _Alloc> bool std::operator<(const __cxx11::basic_string<_CharT, _Traits, _Allocator>&, const __cxx11::basic_string<_CharT, _Traits, _Allocator>&)'
 3874 |     operator<(const basic_string<_CharT, _Traits, _Alloc>& __lhs,
      |     ^~~~~~~~
/usr/include/c++/14/bits/basic_string.h:3874:5: note:   template argument deduction/substitution failed:
a.cc:12:12: note:   'std::basic_ostream<char>' is not derived from 'const std::__cxx11::basic_string<_CharT, _Traits, _Allocator>'
   12 | #define nl '\n'
      |            ^~~~
a.cc:50:21: note: in expansion of macro 'nl'
   50 |         cout << n < nl;
      |                     ^~
/usr/include/c++/14/bits/basic_string.h:3888:5: note: candidate: 'template<class _CharT, class _Traits, class _Alloc> bool std::operator<(const __cxx11::basic_string<_CharT, _Traits, _Allocator>&, const _CharT*)'
 3888 |     operator<(const basic_string<_CharT, _Traits, _Alloc>& __lhs,
      |     ^~~~~~~~
/usr/include/c++/14/bits/basic_string.h:3888:5: note:   template argument deduction/substitution failed:
a.cc:12:12: note:   'std::basic_ostream<char>' is not derived from 'const std::__cxx11::basic_string<_CharT, _Traits, _Allocator>'
   12 | #define nl '\n'
      |            ^~~~
a.cc:50:21: note: in expansion of macro 'nl'
   50 |         cout << n < nl;
      |                     ^~
/usr/include/c++/14/bits/basic_string.h:3901:5: note: candidate: 'template<class _CharT, class _Traits, class _Alloc> bool std::operator<(const _CharT*, const __cxx11::basic_string<_CharT, _Traits, _Allocator>&)'
 3901 |     operator<(const _CharT* __lhs,
      |     ^~~~~~~~
/usr/include/c++/14/bits/basic_string.h:3901:5: note:   template argument deduction/substitution failed:
a.cc:12:12: note:   mismatched types 'const _CharT*' and 'std::basic_ostream<char>'
   12 | #define nl '\n'
      |            ^~~~
a.cc:50:21: note: in expansion of macro 'nl'
   50 |         cout << n < nl;
      |                     ^~
In file included from /usr/include/c++/14/bits/memory_resource.h:47,
                 from /usr/include/c++/14/string:68:
/usr/include/c++/14/tuple:2600:5: note: candidate: 'template<class ... _TElements, class ... _UElements> constexpr bool std::operator<(const tuple<_UTypes ...>&, const tuple<_Elements ...>&)'
 2600 |     operator<(const tuple<_TElements...>& __t,
      |     ^~~~~~~~
/usr/include/c++/14/tuple:2600:5: note:   template argument deduction/substitution failed:
a.cc:12:12: note:   'std::basic_ostream<char>' is not derived from 'const std::tuple<_UTypes ...>'
   12 | #define nl '\n'
      |            ^~~~
a.cc:50:21: note: in expansion of macro 'nl'
   50 |         cout << n < nl;
      |                     ^~
In file included from /usr/include/c++/14/map:63,
                 from a.cc:5:
/usr/include/c++/14/bits/stl_map.h:1550:5: note: candidate: 'template<class _Key, class _Tp, class _Compare, class _Alloc> bool std::operator<(const map<_Key, _Tp, _Compare, _Allocator>&, const map<_Key, _Tp, _Compare, _Allocator>&)'
 1550 |     operator<(const map<_Key, _Tp, _Compare, _Alloc>& __x,
      |     ^~~~~~~~
/usr/include/c++/14/bits/stl_map.h:1550:5: note:   template argument deduction/substitution failed:
a.cc:12:12: note:   'std::basic_ostream<char>' is not derived from 'const std::map<_Key, _Tp, _Compare, _Allocator>'
   12 | #define nl '\n'
      |            ^~~~
a.cc:50:21: note: in expansion of macro 'nl'
   50 |         cout << n < nl;
      |                     ^~
In file included from /usr/include/c++/14/map:64:
/usr/include/c++/14/bits/stl_multimap.h:1172:5: note: candidate: 'template<class _Key, class _Tp, class _Compare, class _Alloc> bool std::operator<(const multimap<_Key, _Tp, _Compare, _Allocator>&, const multimap<_Key, _Tp, _Compare, _Allocator>&)'
 1172 |     operator<(const multimap<_Key, _Tp, _Compare, _Alloc>& __x,
      |