rt.C++17代码如下：

#include<bits/stdc++.h>
using namespace std;
set<int> data;
int main(){
    string dn;
    cin>>dn;
    string tmp;
    int tmp2=0;
    for (int i=0;i<stoi(dn);i++){
        cin>>tmp;tmp2=stoi(tmp);data.insert(tmp2);
    };
    cout<<data.size()<<endl;
    for (int i: data){
        cout<<i<<" ";
    };
    return 0;
};

错误信息:

/tmp/compiler_okhsbcgx/src: 在函数‘int main()’中:
/tmp/compiler_okhsbcgx/src:10:33: 错误：对‘data’的引用有歧义
   10 |         cin>>tmp;tmp2=stoi(tmp);data.insert(tmp2);
      |                                 ^~~~
In file included from /nix/store/fdbr19mgwzmp1f17nbd9pqjv9vl9kzrq-luogu-gcc-11.2.0/include/c++/11.2.0/string:54,
                 from /nix/store/fdbr19mgwzmp1f17nbd9pqjv9vl9kzrq-luogu-gcc-11.2.0/include/c++/11.2.0/bits/locale_classes.h:40,
                 from /nix/store/fdbr19mgwzmp1f17nbd9pqjv9vl9kzrq-luogu-gcc-11.2.0/include/c++/11.2.0/bits/ios_base.h:41,
                 from /nix/store/fdbr19mgwzmp1f17nbd9pqjv9vl9kzrq-luogu-gcc-11.2.0/include/c++/11.2.0/ios:42,
                 from /nix/store/fdbr19mgwzmp1f17nbd9pqjv9vl9kzrq-luogu-gcc-11.2.0/include/c++/11.2.0/istream:38,
                 from /nix/store/fdbr19mgwzmp1f17nbd9pqjv9vl9kzrq-luogu-gcc-11.2.0/include/c++/11.2.0/sstream:38,
                 from /nix/store/fdbr19mgwzmp1f17nbd9pqjv9vl9kzrq-luogu-gcc-11.2.0/include/c++/11.2.0/complex:45,
                 from /nix/store/fdbr19mgwzmp1f17nbd9pqjv9vl9kzrq-luogu-gcc-11.2.0/include/c++/11.2.0/ccomplex:39,
                 from /nix/store/fdbr19mgwzmp1f17nbd9pqjv9vl9kzrq-luogu-gcc-11.2.0/include/c++/11.2.0/x86_64-unknown-linux-gnu/bits/stdc++.h:54,
                 from /tmp/compiler_okhsbcgx/src:1:
/nix/store/fdbr19mgwzmp1f17nbd9pqjv9vl9kzrq-luogu-gcc-11.2.0/include/c++/11.2.0/bits/range_access.h:319:5: 附注：备选为： ‘template<class _Tp> constexpr const _Tp* std::data(std::initializer_list<_Tp>)’
  319 |     data(initializer_list<_Tp> __il) noexcept
      |     ^~~~
/nix/store/fdbr19mgwzmp1f17nbd9pqjv9vl9kzrq-luogu-gcc-11.2.0/include/c++/11.2.0/bits/range_access.h:310:5: 附注：         ‘template<class _Tp, long unsigned int _Nm> constexpr _Tp* std::data(_Tp (&)[_Nm])’
  310 |     data(_Tp (&__array)[_Nm]) noexcept
      |     ^~~~
/nix/store/fdbr19mgwzmp1f17nbd9pqjv9vl9kzrq-luogu-gcc-11.2.0/include/c++/11.2.0/bits/range_access.h:300:5: 附注：         ‘template<class _Container> constexpr decltype (__cont.data()) std::data(const _Container&)’
  300 |     data(const _Container& __cont) noexcept(noexcept(__cont.data()))
      |     ^~~~
/nix/store/fdbr19mgwzmp1f17nbd9pqjv9vl9kzrq-luogu-gcc-11.2.0/include/c++/11.2.0/bits/range_access.h:290:5: 附注：         ‘template<class _Container> constexpr decltype (__cont.data()) std::data(_Container&)’
  290 |     data(_Container& __cont) noexcept(noexcept(__cont.data()))
      |     ^~~~
/tmp/compiler_okhsbcgx/src:3:10: 附注：         ‘std::set<int> data’
    3 | set<int> data;
      |          ^~~~
/tmp/compiler_okhsbcgx/src:12:11: 错误：对‘data’的引用有歧义
   12 |     cout<<data.size()<<endl;
      |           ^~~~
In file included from /nix/store/fdbr19mgwzmp1f17nbd9pqjv9vl9kzrq-luogu-gcc-11.2.0/include/c++/11.2.0/string:54,
                 from /nix/store/fdbr19mgwzmp1f17nbd9pqjv9vl9kzrq-luogu-gcc-11.2.0/include/c++/11.2.0/bits/locale_classes.h:40,
                 from /nix/store/fdbr19mgwzmp1f17nbd9pqjv9vl9kzrq-luogu-gcc-11.2.0/include/c++/11.2.0/bits/ios_base.h:41,
                 from /nix/store/fdbr19mgwzmp1f17nbd9pqjv9vl9kzrq-luogu-gcc-11.2.0/include/c++/11.2.0/ios:42,
                 from /nix/store/fdbr19mgwzmp1f17nbd9pqjv9vl9kzrq-luogu-gcc-11.2.0/include/c++/11.2.0/istream:38,
                 from /nix/store/fdbr19mgwzmp1f17nbd9pqjv9vl9kzrq-luogu-gcc-11.2.0/include/c++/11.2.0/sstream:38,
                 from /nix/store/fdbr19mgwzmp1f17nbd9pqjv9vl9kzrq-luogu-gcc-11.2.0/include/c++/11.2.0/complex:45,
                 from /nix/store/fdbr19mgwzmp1f17nbd9pqjv9vl9kzrq-luogu-gcc-11.2.0/include/c++/11.2.0/ccomplex:39,
                 from /nix/store/fdbr19mgwzmp1f17nbd9pqjv9vl9kzrq-luogu-gcc-11.2.0/include/c++/11.2.0/x86_64-unknown-linux-gnu/bits/stdc++.h:54,
                 from /tmp/compiler_okhsbcgx/src:1:
/nix/store/fdbr19mgwzmp1f17nbd9pqjv9vl9kzrq-luogu-gcc-11.2.0/include/c++/11.2.0/bits/range_access.h:319:5: 附注：备选为： ‘template<class _Tp> constexpr const _Tp* std::data(std::initializer_list<_Tp>)’
  319 |     data(initializer_list<_Tp> __il) noexcept
      |     ^~~~
/nix/store/fdbr19mgwzmp1f17nbd9pqjv9vl9kzrq-luogu-gcc-11.2.0/include/c++/11.2.0/bits/range_access.h:310:5: 附注：         ‘template<class _Tp, long unsigned int _Nm> constexpr _Tp* std::data(_Tp (&)[_Nm])’
  310 |     data(_Tp (&__array)[_Nm]) noexcept
      |     ^~~~
/nix/store/fdbr19mgwzmp1f17nbd9pqjv9vl9kzrq-luogu-gcc-11.2.0/include/c++/11.2.0/bits/range_access.h:300:5: 附注：         ‘template<class _Container> constexpr decltype (__cont.data()) std::data(const _Container&)’
  300 |     data(const _Container& __cont) noexcept(noexcept(__cont.data()))
      |     ^~~~
/nix/store/fdbr19mgwzmp1f17nbd9pqjv9vl9kzrq-luogu-gcc-11.2.0/include/c++/11.2.0/bits/range_access.h:290:5: 附注：         ‘template<class _Container> constexpr decltype (__cont.data()) std::data(_Container&)’
  290 |     data(_Container& __cont) noexcept(noexcept(__cont.data()))
      |     ^~~~
/tmp/compiler_okhsbcgx/src:3:10: 附注：         ‘std::set<int> data’
    3 | set<int> data;
      |          ^~~~
/tmp/compiler_okhsbcgx/src:13:17: 错误：对‘data’的引用有歧义
   13 |     for (int i: data){
      |                 ^~~~
In file included from /nix/store/fdbr19mgwzmp1f17nbd9pqjv9vl9kzrq-luogu-gcc-11.2.0/include/c++/11.2.0/string:54,
                 from /nix/store/fdbr19mgwzmp1f17nbd9pqjv9vl9kzrq-luogu-gcc-11.2.0/include/c++/11.2.0/bits/locale_classes.h:40,
                 from /nix/store/fdbr19mgwzmp1f17nbd9pqjv9vl9kzrq-luogu-gcc-11.2.0/include/c++/11.2.0/bits/ios_base.h:41,
                 from /nix/store/fdbr19mgwzmp1f17nbd9pqjv9vl9kzrq-luogu-gcc-11.2.0/include/c++/11.2.0/ios:42,
                 from /nix/store/fdbr19mgwzmp1f17nbd9pqjv9vl9kzrq-luogu-gcc-11.2.0/include/c++/11.2.0/istream:38,
                 from /nix/store/fdbr19mgwzmp1f17nbd9pqjv9vl9kzrq-luogu-gcc-11.2.0/include/c++/11.2.0/sstream:38,
                 from /nix/store/fdbr19mgwzmp1f17nbd9pqjv9vl9kzrq-luogu-gcc-11.2.0/include/c++/11.2.0/complex:45,
                 from /nix/store/fdbr19mgwzmp1f17nbd9pqjv9vl9kzrq-luogu-gcc-11.2.0/include/c++/11.2.0/ccomplex:39,
                 from /nix/store/fdbr19mgwzmp1f17nbd9pqjv9vl9kzrq-luogu-gcc-11.2.0/include/c++/11.2.0/x86_64-unknown-linux-gnu/bits/stdc++.h:54,
                 from /tmp/compiler_okhsbcgx/src:1:
/nix/store/fdbr19mgwzmp1f17nbd9pqjv9vl9kzrq-luogu-gcc-11.2.0/include/c++/11.2.0/bits/range_access.h:319:5: 附注：备选为： ‘template<class _Tp> constexpr const _Tp* std::data(std::initializer_list<_Tp>)’
  319 |     data(initializer_list<_Tp> __il) noexcept
      |     ^~~~
/nix/store/fdbr19mgwzmp1f17nbd9pqjv9vl9kzrq-luogu-gcc-11.2.0/include/c++/11.2.0/bits/range_access.h:310:5: 附注：         ‘template<class _Tp, long unsigned int _Nm> constexpr _Tp* std::data(_Tp (&)[_Nm])’
  310 |     data(_Tp (&__array)[_Nm]) noexcept
      |     ^~~~
/nix/store/fdbr19mgwzmp1f17nbd9pqjv9vl9kzrq-luogu-gcc-11.2.0/include/c++/11.2.0/bits/range_access.h:300:5: 附注：         ‘template<class _Container> constexpr decltype (__cont.data()) std::data(const _Container&)’
  300 |     data(const _Container& __cont) noexcept(noexcept(__cont.data()))
      |     ^~~~
/nix/store/fdbr19mgwzmp1f17nbd9pqjv9vl9kzrq-luogu-gcc-11.2.0/include/c++/11.2.0/bits/range_access.h:290:5: 附注：         ‘template<class _Container> constexpr decltype (__cont.data()) std::data(_Container&)’
  290 |     data(_Container& __cont) noexcept(noexcept(__cont.data()))
      |     ^~~~
/tmp/compiler_okhsbcgx/src:3:10: 附注：         ‘std::set<int> data’
    3 | set<int> data;
      |          ^~~~