Language: C++

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

/* REPmacro */
#define REP(i,n) for(int i=0,i##_len=(n);i<i##_len;++i)
#define REPR(i,n) for(int i=((int)(n)-1);i>=0;--i)
#define FOR(i,m,n) for(int i=(int)(m);i<(int)(n);++i)

/*alias*/
#define ALL(x) (x).begin(),(x).end()
#define SZ(x) ((int)(x).size())
#define F first
#define S second
#define PB push_back
#define MP make_pair 

#define y0 y3487465
#define y1 y8687969
#define j0 j1347829
#define j1 j234892
#define next asdnext
#define prev asdprev

/*using*/
using ll = long long;
using ull = unsigned long long;
using unsi = unsigned;
using vi = vector<int>;
using vvi = vector<vi>;
using vvvi = vector<vvi>;
using pii = pair<int, int>;
using db = double;
using plex = complex<double>;
using vs = vector<string>;

/*template*/
template<class T>inline bool amax(T &a, const T &b) { if (a<b) { a=b; return 1; } return 0; }
template<class T>inline bool amin(T &a, const T &b) { if (b<a) { a=b; return 1; } return 0; }

/* func */

/*struct*/
struct aaa{
    aaa(){
        cin.tie(0); ios::sync_with_stdio(0); cout<<fixed<<setprecision(20);
    };
}aaaaaaa;

/* const */
const int INF = 1001001001;
const ll LINF = 1001001001001001001ll;
const int MOD = 1e9 + 7; //10^9
const db EPS = 1e-9;
const int dx[] = {0, 1, 0, -1, 1, -1, 1, -1}, dy[] = {1, 0, -1, 0, 1, -1, -1, 1};

//#define int ll
//#define int long long

signed main()
{

  //まちがえとわかっていながら出す。昔これで悩んだから置いとく
  
  int n; cin >> n;
  vi v1(n);
  REP(i,3*n)
    cin >> v1[i];
  
sort(ALL(v1));
  
  auto f,m,e;
  vector<tuple<int,int,int>> t;
  
  for(int i = 0; i < n; ++i){
  f = v1[i];
  t.PB(f,m,n);
  }
  
  int &o = get<0>(t);
  cout << o;
  return 0;
}

Compiler output:
a.cc: In function 'int main()':
a.cc:71:3: error: declaration of 'auto f' has no initializer
   71 |   auto f,m,e;
      |   ^~~~
a.cc:71:3: error: declaration of 'auto m' has no initializer
a.cc:71:3: error: declaration of 'auto e' has no initializer
a.cc:79:18: error: no matching function for call to 'get<0>(std::vector<std::tuple<int, int, int> >&)'
   79 |   int &o = get<0>(t);
      |            ~~~~~~^~~
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,
                 from a.cc:1:
/usr/include/c++/14/bits/stl_pair.h:1250:5: note: candidate: 'template<long unsigned int _Int, class _Tp1, class _Tp2> constexpr typename std::tuple_element<_Int, std::pair<_Tp1, _Tp2> >::type& std::get(pair<_Tp1, _Tp2>&)'
 1250 |     get(pair<_Tp1, _Tp2>& __in) noexcept
      |     ^~~
/usr/include/c++/14/bits/stl_pair.h:1250:5: note:   template argument deduction/substitution failed:
a.cc:79:18: note:   'std::vector<std::tuple<int, int, int> >' is not derived from 'std::pair<_Tp1, _Tp2>'
   79 |   int &o = get<0>(t);
      |            ~~~~~~^~~
/usr/include/c++/14/bits/stl_pair.h:1255:5: note: candidate: 'template<long unsigned int _Int, class _Tp1, class _Tp2> constexpr typename std::tuple_element<_Int, std::pair<_Tp1, _Tp2> >::type&& std::get(pair<_Tp1, _Tp2>&&)'
 1255 |     get(pair<_Tp1, _Tp2>&& __in) noexcept
      |     ^~~
/usr/include/c++/14/bits/stl_pair.h:1255:5: note:   template argument deduction/substitution failed:
a.cc:79:18: note:   'std::vector<std::tuple<int, int, int> >' is not derived from 'std::pair<_Tp1, _Tp2>'
   79 |   int &o = get<0>(t);
      |            ~~~~~~^~~
/usr/include/c++/14/bits/stl_pair.h:1260:5: note: candidate: 'template<long unsigned int _Int, class _Tp1, class _Tp2> constexpr const typename std::tuple_element<_Int, std::pair<_Tp1, _Tp2> >::type& std::get(const pair<_Tp1, _Tp2>&)'
 1260 |     get(const pair<_Tp1, _Tp2>& __in) noexcept
      |     ^~~
/usr/include/c++/14/bits/stl_pair.h:1260:5: note:   template argument deduction/substitution failed:
a.cc:79:18: note:   'std::vector<std::tuple<int, int, int> >' is not derived from 'const std::pair<_Tp1, _Tp2>'
   79 |   int &o = get<0>(t);
      |            ~~~~~~^~~
/usr/include/c++/14/bits/stl_pair.h:1265:5: note: candidate: 'template<long unsigned int _Int, class _Tp1, class _Tp2> constexpr const typename std::tuple_element<_Int, std::pair<_Tp1, _Tp2> >::type&& std::get(const pair<_Tp1, _Tp2>&&)'
 1265 |     get(const pair<_Tp1, _Tp2>&& __in) noexcept
      |     ^~~
/usr/include/c++/14/bits/stl_pair.h:1265:5: note:   template argument deduction/substitution failed:
a.cc:79:18: note:   'std::vector<std::tuple<int, int, int> >' is not derived from 'const std::pair<_Tp1, _Tp2>'
   79 |   int &o = get<0>(t);
      |            ~~~~~~^~~
In file included from /usr/include/c++/14/bits/memory_resource.h:47,
                 from /usr/include/c++/14/string:68,
                 from /usr/include/c++/14/bitset:52,
                 from /usr/include/x86_64-linux-gnu/c++/14/bits/stdc++.h:52:
/usr/include/c++/14/tuple:2445:5: note: candidate: 'template<long unsigned int __i, class ... _Elements> constexpr std::__tuple_element_t<__i, std::tuple<_Elements ...> >& std::get(tuple<_Elements ...>&)'
 2445 |     get(tuple<_Elements...>& __t) noexcept
      |     ^~~
/usr/include/c++/14/tuple:2445:5: note:   template argument deduction/substitution failed:
a.cc:79:18: note:   'std::vector<std::tuple<int, int, int> >' is not derived from 'std::tuple<_Elements ...>'
   79 |   int &o = get<0>(t);
      |            ~~~~~~^~~
/usr/include/c++/14/tuple:2451:5: note: candidate: 'template<long unsigned int __i, class ... _Elements> constexpr std::__tuple_element_t<__i, std::tuple<_Elements ...> >& std::get(const tuple<_Elements ...>&)'
 2451 |     get(const tuple<_Elements...>& __t) noexcept
      |     ^~~
/usr/include/c++/14/tuple:2451:5: note:   template argument deduction/substitution failed:
a.cc:79:18: note:   'std::vector<std::tuple<int, int, int> >' is not derived from 'const std::tuple<_Elements ...>'
   79 |   int &o = get<0>(t);
      |            ~~~~~~^~~
/usr/include/c++/14/tuple:2457:5: note: candidate: 'template<long unsigned int __i, class ... _Elements> constexpr std::__tuple_element_t<__i, std::tuple<_Elements ...> >&& std::get(tuple<_Elements ...>&&)'
 2457 |     get(tuple<_Elements...>&& __t) noexcept
      |     ^~~
/usr/include/c++/14/tuple:2457:5: note:   template argument deduction/substitution failed:
a.cc:79:18: note:   'std::vector<std::tuple<int, int, int> >' is not derived from 'std::tuple<_Elements ...>'
   79 |   int &o = get<0>(t);
      |            ~~~~~~^~~
/usr/include/c++/14/tuple:2466:5: note: candidate: 'template<long unsigned int __i, class ... _Elements> constexpr std::__tuple_element_t<__i, std::tuple<_Elements ...> >&& std::get(const tuple<_Elements ...>&&)'
 2466 |     get(const tuple<_Elements...>&& __t) noexcept
      |     ^~~
/usr/include/c++/14/tuple:2466:5: note:   template argument deduction/substitution failed:
a.cc:79:18: note:   'std::vector<std::tuple<int, int, int> >' is not derived from 'const std::tuple<_Elements ...>'
   79 |   int &o = get<0>(t);
      |            ~~~~~~^~~
In file included from /usr/include/c++/14/functional:65,
                 from /usr/include/x86_64-linux-gnu/c++/14/bits/stdc++.h:53:
/usr/include/c++/14/array:390:5: note: candidate: 'template<long unsigned int _Int, class _Tp, long unsigned int _Nm> constexpr _Tp& std::get(array<_Tp, _Nm>&)'
  390 |     get(array<_Tp, _Nm>& __arr) noexcept
      |     ^~~
/usr/include/c++/14/array:390:5: note:   template argument deduction/substitution failed:
a.cc:79:18: note:   'std::vector<std::tuple<int, int, int> >' is not derived from 'std::array<_Tp, _Nm>'
   79 |   int &o = get<0>(t);
      |            ~~~~~~^~~
/usr/include/c++/14/array:399:5: note: candidate: 'template<long unsigned int _Int, class _Tp, long unsigned int _Nm> constexpr _Tp&& std::get(array<_Tp, _Nm>&&)'
  399 |     get(array<_Tp, _Nm>&& __arr) noexcept
      |     ^~~
/usr/include/c++/14/array:399:5: note:   template argument deduction/substitution failed:
a.cc:79:18: note:   'std::vector<std::tuple<int, int, int> >' is not derived from 'std::array<_Tp, _Nm>'
   79 |   int &o = get<0>(t);
      |            ~~~~~~^~~
/usr/include/c++/14/array:408:5: note: candidate: 'template<long unsigned int _Int, class _Tp, long unsigned int _Nm> constexpr const _Tp& std::get(const array<_Tp, _Nm>&)'
  408 |     get(const array<_Tp, _Nm>& __arr) noexcept
      |     ^~~
/usr/include/c++/14/array:408:5: note:   template argument deduction/substitution failed:
a.cc:79:18: note:   'std::vector<std::tuple<int, int, int> >' is not derived from 'const std::array<_Tp, _Nm>'
   79 |   int &o = get<0>(t);
      |            ~~~~~~^~~
/usr/include/c++/14/array:417:5: note: candidate: 'template<long unsigned int _Int, class _Tp, long unsigned int _Nm> constexpr const _Tp&& std::get(const array<_Tp, _Nm>&&)'
  417 |     get(const array<_Tp, _Nm>&& __arr) noexcept
      |     ^~~
/usr/include/c++/14/array:417:5: note:   template argument deduction/substitution failed:
a.cc:79:18: note:   'std::vector<std::tuple<int, int, int> >' is not derived from 'const std::array<_Tp, _Nm>'
   79 |   int &o = get<0>(t);
      |            ~~~~~~^~~
/usr/include/c++/14/bits/stl_pair.h:1272:5: note: candidate: 'template<class _Tp, class _Up> constexpr _Tp& std::get(pair<_T1, _T2>&)'
 1272 |     get(pair<_Tp, _Up>& __p) noexcept
      |     ^~~
/usr/include/c++/14/bits/stl_pair.h:1272:5: note:   template argument deduction/substitution failed:
a.cc:79:18: error: type/value mismatch at argument 1 in template parameter list for 'template<class _Tp, class _Up> constexpr _Tp& std::get(pair<_T1, _T2>&)'
   79 |   int &o = get<0>(t);
      |            ~~~~~~^~~
a.cc:79:18: note:   expected a type, got '0'
/usr/include/c++/14/bits/stl_pair.h:1277:5: note: candidate: 'template<class _Tp, class _Up> constexpr const _Tp& std::get(const pair<_T1, _T2>&)'
 1277 |     get(const pair<_Tp, _Up>& __p) noexcept
      |     ^~~
/usr/include/c++/14/bits/stl_pair.h:1277:5: note:   template argument deduction/substitution failed:
a.cc:79:18: error: type/value mismatch at argument 1 in template parameter list for 'template<class _Tp, class _Up> constexpr const _Tp& std::get(const pair<_T1, _T2>&)'
   79 |   int &o = get<0>(t);
      |            ~~~~~~^~~
a.cc:79:18: note:   expected a type, got '0'
/usr/include/c++/14/bits/stl_pair.h:1282:5: note: candidate: 'template<class _Tp, class _Up> constexpr _Tp&& std::get(pair<_T1, _T2>&&)'
 1282 |     get(pair<_Tp, _Up>&& __p) noexcept
      |     ^~~
/usr/include/c++/14/bits/stl_pair.h:1282:5: note:   template argument deduction/substitution failed:
a.cc:79:18: error: type/value mismatch at argument 1 in template parameter list for 'template<class _Tp, class _Up> constexpr _Tp&& std::get(pair<_T1, _T2>&&)'
   79 |   int &o = get<0>(t);
      |            ~~~~~~^~~
a.cc:79:18: note:   expected a type, got '0'
/usr/include/c++/14/bits/stl_pair.h:1287:5: note: candidate: 'template<class _Tp, class _Up> constexpr const _Tp&& std::get(const pair<_T1, _T2>&&)'
 1287 |     get(const pair<_Tp, _Up>&& __p) noexcept
      |     ^~~
/usr/include/c++/14/bits/stl_pair.h:1287:5: note:   template argument deduction/substitution failed:
a.cc:79:18: error: type/value mismatch at argument 1 in template parameter list for 'template<class _Tp, class _Up> constexpr const _Tp&& std::get(const pair<_T1, _T2>&&)'
   79 |   int &o = get<0>(t);
      |            ~~~~~~^~~
a.cc:79:18: note:   expected a type, got '0'
/usr/include/c++/14/bits/stl_pair.h:1292:5: note: candidate: 'template<class _Tp, class _Up> constexpr _Tp& std::get(pair<_Up, _Tp>&)'
 1292 |     get(pair<_Up, _Tp>& __p) noexcept
      |     ^~~
/usr/include/c++/14/bits/stl_pair.h:1292:5: note:   template argument deduction/substitution failed:
a.cc:79:18: error: type/value mismatch at argument 1 in template parameter list for 'template<class _Tp, class _Up> constexpr _Tp& std::get(pair<_Up, _Tp>&)'
   79 |   int &o = get<0>(t);