Language: C++

///-----Bismillahir Rahmanir Rahim-----///

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

///---FAST I/O---///
#define Boost() ios_base::sync_with_stdio(0);cin.tie(0);cout.tie(0);

///---DATA TYPE---///
typedef long long ll;
typedef long long int lli;
typedef vector<int> vi;
typedef vector<ll> vl;
typedef vector<vi> vvi;
typedef vector<vl> vvl;
typedef pair<int,int> pii;
typedef pair<double, double> pdd;
typedef pair<ll, ll> pll;
typedef vector<pii> vii;
typedef vector<pll> vll;
typedef vector<int>::iterator vit;
typedef set<int>::iterator sit;

///---LOOP---///
#define rep0(i,n) for(i=0;i<n;i++)
#define rep1(i,n) for(i=1;i<=n;i++)

///---I/O---///
#define sf scanf
#define pf printf

///---OTHERS---///
#define pb push_back
#define all(c)		c.begin(),c.end()
#define MK make_pair
#define F first
#define S second
#define endl '\n'


///---INITIALIZATION---//
#define mem(a,b) memset(a, b, sizeof(a) )

///---CALCULATE---///
#define gcd(a,b) __gcd(a,b)
#define lcm(a,b) (a*(b/gcd(a,b)))
#define sqr(a) ((a) * (a))

///---BIT OPERATION---///
inline bool checkBit(ll n, int i)
{
    return n&(1LL<<i);
}
inline ll setBit(ll n, int i)
{
    return n|(1LL<<i);;
}
inline ll resetBit(ll n, int i)
{
    return n&(~(1LL<<i));
}

///------String/Char Related Functions-----///
string makeintString(int x)
{
    stringstream ss;
    ss << x;
    string str = ss.str();
    ///cout<<str<<endl;
    return str;
}
string makellString(ll x)
{
    stringstream ss;
    ss << x;
    string str = ss.str();
    ///cout<<str<<endl;
    return str;
}
char cpp(char c)
{
    return static_cast<char>(c + 1);
}

///------------Sorting STL----------///
struct func
{
	//this is a sample overloading function for sorting stl
	bool operator()(pii const &a, pii const &b)
	{
		if(a.F==b.F)
			return (a.S<b.S);
		return (a.F<b.F);
	}
};

///---CONSTANT---///
const double PI = acos(-1);
const double eps = 1e-9;
const int inf = 2000000000;
const ll infLL = 9000000000000000000;
#define MOD 1000000007

int main()
{
    Boost();

    int t;
    t=1;
    //cin>>t;
    while(t--)
    {
      int n;
      cin>>n;
      cout<<n%1000==0?0:1000-(n%1000)<<endl;
    }
    return 0;
}


Compiler output:
a.cc: In function 'int main()':
a.cc:115:19: error: no match for 'operator==' (operand types are 'std::basic_ostream<char>' and 'int')
  115 |       cout<<n%1000==0?0:1000-(n%1000)<<endl;
      |       ~~~~~~~~~~~~^~~
      |           |         |
      |           |         int
      |           std::basic_ostream<char>
a.cc:115:19: note: candidate: 'operator==(int, int)' (built-in)
  115 |       cout<<n%1000==0?0:1000-(n%1000)<<endl;
      |       ~~~~~~~~~~~~^~~
a.cc:115:19: note:   no known conversion for argument 1 from 'std::basic_ostream<char>' to 'int'
In file included from /usr/include/c++/14/regex:68,
                 from /usr/include/x86_64-linux-gnu/c++/14/bits/stdc++.h:181,
                 from a.cc:3:
/usr/include/c++/14/bits/regex.h:1103:5: note: candidate: 'template<class _BiIter> bool std::__cxx11::operator==(const sub_match<_BiIter>&, const sub_match<_BiIter>&)'
 1103 |     operator==(const sub_match<_BiIter>& __lhs, const sub_match<_BiIter>& __rhs)
      |     ^~~~~~~~
/usr/include/c++/14/bits/regex.h:1103:5: note:   template argument deduction/substitution failed:
a.cc:115:21: note:   'std::basic_ostream<char>' is not derived from 'const std::__cxx11::sub_match<_BiIter>'
  115 |       cout<<n%1000==0?0:1000-(n%1000)<<endl;
      |                     ^
/usr/include/c++/14/bits/regex.h:1199:5: note: candidate: 'template<class _Bi_iter, class _Ch_traits, class _Ch_alloc> bool std::__cxx11::operator==(__sub_match_string<_Bi_iter, _Ch_traits, _Ch_alloc>&, const sub_match<_BiIter>&)'
 1199 |     operator==(const __sub_match_string<_Bi_iter, _Ch_traits, _Ch_alloc>& __lhs,
      |     ^~~~~~~~
/usr/include/c++/14/bits/regex.h:1199:5: note:   template argument deduction/substitution failed:
a.cc:115:21: note:   'std::basic_ostream<char>' is not derived from 'std::__cxx11::__sub_match_string<_Bi_iter, _Ch_traits, _Ch_alloc>'
  115 |       cout<<n%1000==0?0:1000-(n%1000)<<endl;
      |                     ^
/usr/include/c++/14/bits/regex.h:1274:5: note: candidate: 'template<class _Bi_iter, class _Ch_traits, class _Ch_alloc> bool std::__cxx11::operator==(const sub_match<_BiIter>&, __sub_match_string<_Bi_iter, _Ch_traits, _Ch_alloc>&)'
 1274 |     operator==(const sub_match<_Bi_iter>& __lhs,
      |     ^~~~~~~~
/usr/include/c++/14/bits/regex.h:1274:5: note:   template argument deduction/substitution failed:
a.cc:115:21: note:   'std::basic_ostream<char>' is not derived from 'const std::__cxx11::sub_match<_BiIter>'
  115 |       cout<<n%1000==0?0:1000-(n%1000)<<endl;
      |                     ^
/usr/include/c++/14/bits/regex.h:1366:5: note: candidate: 'template<class _Bi_iter> bool std::__cxx11::operator==(const typename std::iterator_traits<_Iter>::value_type*, const sub_match<_BiIter>&)'
 1366 |     operator==(typename iterator_traits<_Bi_iter>::value_type const* __lhs,
      |     ^~~~~~~~
/usr/include/c++/14/bits/regex.h:1366:5: note:   template argument deduction/substitution failed:
a.cc:115:21: note:   mismatched types 'const std::__cxx11::sub_match<_BiIter>' and 'int'
  115 |       cout<<n%1000==0?0:1000-(n%1000)<<endl;
      |                     ^
/usr/include/c++/14/bits/regex.h:1441:5: note: candidate: 'template<class _Bi_iter> bool std::__cxx11::operator==(const sub_match<_BiIter>&, const typename std::iterator_traits<_Iter>::value_type*)'
 1441 |     operator==(const sub_match<_Bi_iter>& __lhs,
      |     ^~~~~~~~
/usr/include/c++/14/bits/regex.h:1441:5: note:   template argument deduction/substitution failed:
a.cc:115:21: note:   'std::basic_ostream<char>' is not derived from 'const std::__cxx11::sub_match<_BiIter>'
  115 |       cout<<n%1000==0?0:1000-(n%1000)<<endl;
      |                     ^
/usr/include/c++/14/bits/regex.h:1534:5: note: candidate: 'template<class _Bi_iter> bool std::__cxx11::operator==(const typename std::iterator_traits<_Iter>::value_type&, const sub_match<_BiIter>&)'
 1534 |     operator==(typename iterator_traits<_Bi_iter>::value_type const& __lhs,
      |     ^~~~~~~~
/usr/include/c++/14/bits/regex.h:1534:5: note:   template argument deduction/substitution failed:
a.cc:115:21: note:   mismatched types 'const std::__cxx11::sub_match<_BiIter>' and 'int'
  115 |       cout<<n%1000==0?0:1000-(n%1000)<<endl;
      |                     ^
/usr/include/c++/14/bits/regex.h:1613:5: note: candidate: 'template<class _Bi_iter> bool std::__cxx11::operator==(const sub_match<_BiIter>&, const typename std::iterator_traits<_Iter>::value_type&)'
 1613 |     operator==(const sub_match<_Bi_iter>& __lhs,
      |     ^~~~~~~~
/usr/include/c++/14/bits/regex.h:1613:5: note:   template argument deduction/substitution failed:
a.cc:115:21: note:   'std::basic_ostream<char>' is not derived from 'const std::__cxx11::sub_match<_BiIter>'
  115 |       cout<<n%1000==0?0:1000-(n%1000)<<endl;
      |                     ^
/usr/include/c++/14/bits/regex.h:2186:5: note: candidate: 'template<class _Bi_iter, class _Alloc> bool std::__cxx11::operator==(const match_results<_BiIter, _Alloc>&, const match_results<_BiIter, _Alloc>&)'
 2186 |     operator==(const match_results<_Bi_iter, _Alloc>& __m1,
      |     ^~~~~~~~
/usr/include/c++/14/bits/regex.h:2186:5: note:   template argument deduction/substitution failed:
a.cc:115:21: note:   'std::basic_ostream<char>' is not derived from 'const std::__cxx11::match_results<_BiIter, _Alloc>'
  115 |       cout<<n%1000==0?0:1000-(n%1000)<<endl;
      |                     ^
In file included from /usr/include/c++/14/bits/stl_algobase.h:64,
                 from /usr/include/c++/14/algorithm:60,
                 from /usr/include/x86_64-linux-gnu/c++/14/bits/stdc++.h:51:
/usr/include/c++/14/bits/stl_pair.h:1033:5: note: candidate: 'template<class _T1, class _T2> constexpr bool std::operator==(const pair<_T1, _T2>&, const pair<_T1, _T2>&)'
 1033 |     operator==(const pair<_T1, _T2>& __x, const pair<_T1, _T2>& __y)
      |     ^~~~~~~~
/usr/include/c++/14/bits/stl_pair.h:1033:5: note:   template argument deduction/substitution failed:
a.cc:115:21: note:   'std::basic_ostream<char>' is not derived from 'const std::pair<_T1, _T2>'
  115 |       cout<<n%1000==0?0:1000-(n%1000)<<endl;
      |                     ^
In file included from /usr/include/c++/14/bits/stl_algobase.h:67:
/usr/include/c++/14/bits/stl_iterator.h:441:5: note: candidate: 'template<class _Iterator> constexpr bool std::operator==(const reverse_iterator<_Iterator>&, const reverse_iterator<_Iterator>&)'
  441 |     operator==(const reverse_iterator<_Iterator>& __x,
      |     ^~~~~~~~
/usr/include/c++/14/bits/stl_iterator.h:441:5: note:   template argument deduction/substitution failed:
a.cc:115:21: note:   'std::basic_ostream<char>' is not derived from 'const std::reverse_iterator<_Iterator>'
  115 |       cout<<n%1000==0?0:1000-(n%1000)<<endl;
      |                     ^
/usr/include/c++/14/bits/stl_iterator.h:486:5: note: candidate: 'template<class _IteratorL, class _IteratorR> constexpr bool std::operator==(const reverse_iterator<_Iterator>&, const reverse_iterator<_IteratorR>&)'
  486 |     operator==(const reverse_iterator<_IteratorL>& __x,
      |     ^~~~~~~~
/usr/include/c++/14/bits/stl_iterator.h:486:5: note:   template argument deduction/substitution failed:
a.cc:115:21: note:   'std::basic_ostream<char>' is not derived from 'const std::reverse_iterator<_Iterator>'
  115 |       cout<<n%1000==0?0:1000-(n%1000)<<endl;
      |                     ^
/usr/include/c++/14/bits/stl_iterator.h:1667:5: note: candidate: 'template<class _IteratorL, class _IteratorR> constexpr bool std::operator==(const move_iterator<_IteratorL>&, const move_iterator<_IteratorR>&)'
 1667 |     operator==(const move_iterator<_IteratorL>& __x,
      |     ^~~~~~~~
/usr/include/c++/14/bits/stl_iterator.h:1667:5: note:   template argument deduction/substitution failed:
a.cc:115:21: note:   'std::basic_ostream<char>' is not derived from 'const std::move_iterator<_IteratorL>'
  115 |       cout<<n%1000==0?0:1000-(n%1000)<<endl;
      |                     ^
/usr/include/c++/14/bits/stl_iterator.h:1737:5: note: candidate: 'template<class _Iterator> constexpr bool std::operator==(const move_iterator<_IteratorL>&, const move_iterator<_IteratorL>&)'
 1737 |     operator==(const move_iterator<_Iterator>& __x,
      |     ^~~~~~~~
/usr/include/c++/14/bits/stl_iterator.h:1737:5: note:   template argument deduction/substitution failed:
a.cc:115:21: note:   'std::basic_ostream<char>' is not derived from 'const std::move_iterator<_IteratorL>'
  115 |       cout<<n%1000==0?0:1000-(n%1000)<<endl;
      |                     ^
In file included from /usr/include/c++/14/bits/char_traits.h:42,
                 from /usr/include/c++/14/string:42,
                 from /usr/include/c++/14/bitset:52,
                 from /usr/include/x86_64-linux-gnu/c++/14/bits/stdc++.h:52:
/usr/include/c++/14/bits/postypes.h:192:5: note: candidate: 'template<class _StateT> bool std::operator==(const fpos<_StateT>&, const fpos<_StateT>&)'
  192 |     operator==(const fpos<_StateT>& __lhs, const fpos<_StateT>& __rhs)
      |     ^~~~~~~~
/usr/include/c++/14/bits/postypes.h:192:5: note:   template argument deduction/substitution failed:
a.cc:115:21: note:   'std::basic_ostream<char>' is not derived from 'const std::fpos<_StateT>'
  115 |       cout<<n%1000==0?0:1000-(n%1000)<<endl;
      |                     ^
In file included from /usr/include/c++/14/string:43:
/usr/include/c++/14/bits/allocator.h:235:5: note: candidate: 'template<class _T1, class _T2> bool std::operator==(const allocator<_CharT>&, const allocator<_T2>&)'
  235 |     operator==(const allocator<_T1>&, const allocator<_T2>&)
      |     ^~~~~~~~
/usr/include/c++/14/bits/allocator.h:235:5: note:   template argument deduction/substitution failed:
a.cc:115:21: note:   'std::basic_ostream<char>' is not derived from 'const std::allocator<_CharT>'
  115 |       cout<<n%1000==0?0:1000-(n%1000)<<endl;
      |                     ^
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:629:5: note: candidate: 'template<class _CharT, class _Traits> constexpr bool std::operator==(basic_string_view<_CharT, _Traits>, __type_identity_t<ba