Language: C++

#include <iostream>
#include <list>
#include <string>
using namespace std;

int main()
{
    cin.tie(0);
    ios_base::sync_with_stdio(0);

    list<int> l;
    int n;
    cin >> n;

    while(n--)
    {
        string s;
        int a;
        cin >> s;

        if(s == "insert")
        {
            cin >> a;
            l.push_front(a);
        }
        else if(s == "delete")
        {
            cin >> a;
            for (list<int>::iterator it = l.begin(); it != l.end(); it++)
            {
                if(*it == a)
                {
                    l.erase(it);
                    break;
                }
            }
        }
        else if(s == "deleteFirst")
        {
            l.pop_front();
        }
        else if(s == "deleteLast")
        {
            l.pop_back();
        }
    }

    for (list<long>::iterator it = l.begin(); it != l.end(); it++)
    {
        if(it != l.begin())
        {
            cout << " ";
        }
        cout << *it;
    }
    cout << "\n";
}


Compiler output:
a.cc: In function 'int main()':
a.cc:48:43: error: conversion from '_List_iterator<int>' to non-scalar type '_List_iterator<long int>' requested
   48 |     for (list<long>::iterator it = l.begin(); it != l.end(); it++)
      |                                    ~~~~~~~^~
a.cc:48:50: error: no match for 'operator!=' (operand types are 'std::__cxx11::list<long int>::iterator' and 'std::__cxx11::list<int>::iterator')
   48 |     for (list<long>::iterator it = l.begin(); it != l.end(); it++)
      |                                               ~~ ^~ ~~~~~~~
      |                                               |          |
      |                                               |          _List_iterator<int>
      |                                               _List_iterator<long int>
In file included from /usr/include/c++/14/iosfwd:42,
                 from /usr/include/c++/14/ios:40,
                 from /usr/include/c++/14/ostream:40,
                 from /usr/include/c++/14/iostream:41,
                 from a.cc:1:
/usr/include/c++/14/bits/postypes.h:197:5: note: candidate: 'template<class _StateT> bool std::operator!=(const fpos<_StateT>&, const fpos<_StateT>&)'
  197 |     operator!=(const fpos<_StateT>& __lhs, const fpos<_StateT>& __rhs)
      |     ^~~~~~~~
/usr/include/c++/14/bits/postypes.h:197:5: note:   template argument deduction/substitution failed:
a.cc:48:59: note:   'std::__cxx11::list<long int>::iterator' is not derived from 'const std::fpos<_StateT>'
   48 |     for (list<long>::iterator it = l.begin(); it != l.end(); it++)
      |                                                           ^
In file included from /usr/include/c++/14/string:43,
                 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:
/usr/include/c++/14/bits/allocator.h:243:5: note: candidate: 'template<class _T1, class _T2> bool std::operator!=(const allocator<_CharT>&, const allocator<_T2>&)'
  243 |     operator!=(const allocator<_T1>&, const allocator<_T2>&)
      |     ^~~~~~~~
/usr/include/c++/14/bits/allocator.h:243:5: note:   template argument deduction/substitution failed:
a.cc:48:59: note:   'std::__cxx11::list<long int>::iterator' is not derived from 'const std::allocator<_CharT>'
   48 |     for (list<long>::iterator it = l.begin(); it != l.end(); it++)
      |                                                           ^
In file included from /usr/include/c++/14/string:48:
/usr/include/c++/14/bits/stl_iterator.h:455:5: note: candidate: 'template<class _Iterator> constexpr bool std::operator!=(const reverse_iterator<_Iterator>&, const reverse_iterator<_Iterator>&)'
  455 |     operator!=(const reverse_iterator<_Iterator>& __x,
      |     ^~~~~~~~
/usr/include/c++/14/bits/stl_iterator.h:455:5: note:   template argument deduction/substitution failed:
a.cc:48:59: note:   'std::__cxx11::list<long int>::iterator' is not derived from 'const std::reverse_iterator<_Iterator>'
   48 |     for (list<long>::iterator it = l.begin(); it != l.end(); it++)
      |                                                           ^
/usr/include/c++/14/bits/stl_iterator.h:500:5: note: candidate: 'template<class _IteratorL, class _IteratorR> constexpr bool std::operator!=(const reverse_iterator<_Iterator>&, const reverse_iterator<_IteratorR>&)'
  500 |     operator!=(const reverse_iterator<_IteratorL>& __x,
      |     ^~~~~~~~
/usr/include/c++/14/bits/stl_iterator.h:500:5: note:   template argument deduction/substitution failed:
a.cc:48:59: note:   'std::__cxx11::list<long int>::iterator' is not derived from 'const std::reverse_iterator<_Iterator>'
   48 |     for (list<long>::iterator it = l.begin(); it != l.end(); it++)
      |                                                           ^
/usr/include/c++/14/bits/stl_iterator.h:1686:5: note: candidate: 'template<class _IteratorL, class _IteratorR> constexpr bool std::operator!=(const move_iterator<_IteratorL>&, const move_iterator<_IteratorR>&)'
 1686 |     operator!=(const move_iterator<_IteratorL>& __x,
      |     ^~~~~~~~
/usr/include/c++/14/bits/stl_iterator.h:1686:5: note:   template argument deduction/substitution failed:
a.cc:48:59: note:   'std::__cxx11::list<long int>::iterator' is not derived from 'const std::move_iterator<_IteratorL>'
   48 |     for (list<long>::iterator it = l.begin(); it != l.end(); it++)
      |                                                           ^
/usr/include/c++/14/bits/stl_iterator.h:1753:5: note: candidate: 'template<class _Iterator> constexpr bool std::operator!=(const move_iterator<_IteratorL>&, const move_iterator<_IteratorL>&)'
 1753 |     operator!=(const move_iterator<_Iterator>& __x,
      |     ^~~~~~~~
/usr/include/c++/14/bits/stl_iterator.h:1753:5: note:   template argument deduction/substitution failed:
a.cc:48:59: note:   'std::__cxx11::list<long int>::iterator' is not derived from 'const std::move_iterator<_IteratorL>'
   48 |     for (list<long>::iterator it = l.begin(); it != l.end(); it++)
      |                                                           ^
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:1052:5: note: candidate: 'template<class _T1, class _T2> constexpr bool std::operator!=(const pair<_T1, _T2>&, const pair<_T1, _T2>&)'
 1052 |     operator!=(const pair<_T1, _T2>& __x, const pair<_T1, _T2>& __y)
      |     ^~~~~~~~
/usr/include/c++/14/bits/stl_pair.h:1052:5: note:   template argument deduction/substitution failed:
a.cc:48:59: note:   'std::__cxx11::list<long int>::iterator' is not derived from 'const std::pair<_T1, _T2>'
   48 |     for (list<long>::iterator it = l.begin(); it != l.end(); it++)
      |                                                           ^
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:651:5: note: candidate: 'template<class _CharT, class _Traits> constexpr bool std::operator!=(basic_string_view<_CharT, _Traits>, basic_string_view<_CharT, _Traits>)'
  651 |     operator!=(basic_string_view<_CharT, _Traits> __x,
      |     ^~~~~~~~
/usr/include/c++/14/string_view:651:5: note:   template argument deduction/substitution failed:
a.cc:48:59: note:   'std::_List_iterator<long int>' is not derived from 'std::basic_string_view<_CharT, _Traits>'
   48 |     for (list<long>::iterator it = l.begin(); it != l.end(); it++)
      |                                                           ^
/usr/include/c++/14/string_view:658:5: note: candidate: 'template<class _CharT, class _Traits> constexpr bool std::operator!=(basic_string_view<_CharT, _Traits>, __type_identity_t<basic_string_view<_CharT, _Traits> >)'
  658 |     operator!=(basic_string_view<_CharT, _Traits> __x,
      |     ^~~~~~~~
/usr/include/c++/14/string_view:658:5: note:   template argument deduction/substitution failed:
a.cc:48:59: note:   'std::_List_iterator<long int>' is not derived from 'std::basic_string_view<_CharT, _Traits>'
   48 |     for (list<long>::iterator it = l.begin(); it != l.end(); it++)
      |                                                           ^
/usr/include/c++/14/string_view:666:5: note: candidate: 'template<class _CharT, class _Traits> constexpr bool std::operator!=(__type_identity_t<basic_string_view<_CharT, _Traits> >, basic_string_view<_CharT, _Traits>)'
  666 |     operator!=(__type_identity_t<basic_string_view<_CharT, _Traits>> __x,
      |     ^~~~~~~~
/usr/include/c++/14/string_view:666:5: note:   template argument deduction/substitution failed:
a.cc:48:59: note:   'std::_List_iterator<int>' is not derived from 'std::basic_string_view<_CharT, _Traits>'
   48 |     for (list<long>::iterator it = l.begin(); it != l.end(); it++)
      |                                                           ^
/usr/include/c++/14/bits/basic_string.h:3833:5: 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>&)'
 3833 |     operator!=(const basic_string<_CharT, _Traits, _Alloc>& __lhs,
      |     ^~~~~~~~
/usr/include/c++/14/bits/basic_string.h:3833:5: note:   template argument deduction/substitution failed:
a.cc:48:59: note:   'std::__cxx11::list<long int>::iterator' is not derived from 'const std::__cxx11::basic_string<_CharT, _Traits, _Allocator>'
   48 |     for (list<long>::iterator it = l.begin(); it != l.end(); it++)
      |                                                           ^
/usr/include/c++/14/bits/basic_string.h:3847:5: note: candidate: 'template<class _CharT, class _Traits, class _Alloc> bool std::operator!=(const _CharT*, const __cxx11::basic_string<_CharT, _Traits, _Allocator>&)'
 3847 |     operator!=(const _CharT* __lhs,
      |     ^~~~~~~~
/usr/include/c++/14/bits/basic_string.h:3847:5: note:   template argument deduction/substitution failed:
a.cc:48:59: note:   mismatched types 'const _CharT*' and 'std::_List_iterator<long int>'
   48 |     for (list<long>::iterator it = l.begin(); it != l.end(); it++)
      |                                                           ^
/usr/include/c++/14/bits/basic_string.h:3860:5: note: candidate: 'template<class _CharT, class _Traits, class _Alloc> bool std::operator!=(const __cxx11::basic_string<_CharT, _Traits, _Allocator>&, const _CharT*)'
 3860 |     operator!=(const basic_string<_CharT, _Traits, _Alloc>& __lhs,
      |     ^~~~~~~~
/usr/include/c++/14/bits/basic_string.h:3860:5: note:   template argument deduction/substitution failed:
a.cc:48:59: note:   'std::__cxx11::list<long int>::iterator' is not derived from 'const std::__cxx11::basic_string<_CharT, _Traits, _Allocator>'
   48 |     for (list<long>::iterator it = l.begin(); it != l.end(); it++)
      |                                                           ^
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:2613:5: note: candidate: 'template<class ... _TElemen