Language: C++

#include<iostream>
#include<vector>
using namespace std ;

int main()
{
  string S ;
  cin>>S ;
  
  vector<pair<string,int>>day ;
  day.push_back("SUN",7) ;
  day.push_back("MON",6) ;
  day.push_back("TUE",5) ;
  day.push_back("WED",4) ;
  day.push_back("THU",3) ;
  day.push_back("FRI",2) ;
  day.push_back("SAT",1) ;
  
  for(int i=0;i<7;i++) if(S==day.at(i).first) cout<<day.at(i).second ; 
  
  return 0 ;
}

Compiler output:
a.cc: In function 'int main()':
a.cc:11:16: error: no matching function for call to 'std::vector<std::pair<std::__cxx11::basic_string<char>, int> >::push_back(const char [4], int)'
   11 |   day.push_back("SUN",7) ;
      |   ~~~~~~~~~~~~~^~~~~~~~~
In file included from /usr/include/c++/14/vector:66,
                 from a.cc:2:
/usr/include/c++/14/bits/stl_vector.h:1283:7: note: candidate: 'void std::vector<_Tp, _Alloc>::push_back(const value_type&) [with _Tp = std::pair<std::__cxx11::basic_string<char>, int>; _Alloc = std::allocator<std::pair<std::__cxx11::basic_string<char>, int> >; value_type = std::pair<std::__cxx11::basic_string<char>, int>]'
 1283 |       push_back(const value_type& __x)
      |       ^~~~~~~~~
/usr/include/c++/14/bits/stl_vector.h:1283:7: note:   candidate expects 1 argument, 2 provided
/usr/include/c++/14/bits/stl_vector.h:1300:7: note: candidate: 'void std::vector<_Tp, _Alloc>::push_back(value_type&&) [with _Tp = std::pair<std::__cxx11::basic_string<char>, int>; _Alloc = std::allocator<std::pair<std::__cxx11::basic_string<char>, int> >; value_type = std::pair<std::__cxx11::basic_string<char>, int>]'
 1300 |       push_back(value_type&& __x)
      |       ^~~~~~~~~
/usr/include/c++/14/bits/stl_vector.h:1300:7: note:   candidate expects 1 argument, 2 provided
a.cc:12:16: error: no matching function for call to 'std::vector<std::pair<std::__cxx11::basic_string<char>, int> >::push_back(const char [4], int)'
   12 |   day.push_back("MON",6) ;
      |   ~~~~~~~~~~~~~^~~~~~~~~
/usr/include/c++/14/bits/stl_vector.h:1283:7: note: candidate: 'void std::vector<_Tp, _Alloc>::push_back(const value_type&) [with _Tp = std::pair<std::__cxx11::basic_string<char>, int>; _Alloc = std::allocator<std::pair<std::__cxx11::basic_string<char>, int> >; value_type = std::pair<std::__cxx11::basic_string<char>, int>]'
 1283 |       push_back(const value_type& __x)
      |       ^~~~~~~~~
/usr/include/c++/14/bits/stl_vector.h:1283:7: note:   candidate expects 1 argument, 2 provided
/usr/include/c++/14/bits/stl_vector.h:1300:7: note: candidate: 'void std::vector<_Tp, _Alloc>::push_back(value_type&&) [with _Tp = std::pair<std::__cxx11::basic_string<char>, int>; _Alloc = std::allocator<std::pair<std::__cxx11::basic_string<char>, int> >; value_type = std::pair<std::__cxx11::basic_string<char>, int>]'
 1300 |       push_back(value_type&& __x)
      |       ^~~~~~~~~
/usr/include/c++/14/bits/stl_vector.h:1300:7: note:   candidate expects 1 argument, 2 provided
a.cc:13:16: error: no matching function for call to 'std::vector<std::pair<std::__cxx11::basic_string<char>, int> >::push_back(const char [4], int)'
   13 |   day.push_back("TUE",5) ;
      |   ~~~~~~~~~~~~~^~~~~~~~~
/usr/include/c++/14/bits/stl_vector.h:1283:7: note: candidate: 'void std::vector<_Tp, _Alloc>::push_back(const value_type&) [with _Tp = std::pair<std::__cxx11::basic_string<char>, int>; _Alloc = std::allocator<std::pair<std::__cxx11::basic_string<char>, int> >; value_type = std::pair<std::__cxx11::basic_string<char>, int>]'
 1283 |       push_back(const value_type& __x)
      |       ^~~~~~~~~
/usr/include/c++/14/bits/stl_vector.h:1283:7: note:   candidate expects 1 argument, 2 provided
/usr/include/c++/14/bits/stl_vector.h:1300:7: note: candidate: 'void std::vector<_Tp, _Alloc>::push_back(value_type&&) [with _Tp = std::pair<std::__cxx11::basic_string<char>, int>; _Alloc = std::allocator<std::pair<std::__cxx11::basic_string<char>, int> >; value_type = std::pair<std::__cxx11::basic_string<char>, int>]'
 1300 |       push_back(value_type&& __x)
      |       ^~~~~~~~~
/usr/include/c++/14/bits/stl_vector.h:1300:7: note:   candidate expects 1 argument, 2 provided
a.cc:14:16: error: no matching function for call to 'std::vector<std::pair<std::__cxx11::basic_string<char>, int> >::push_back(const char [4], int)'
   14 |   day.push_back("WED",4) ;
      |   ~~~~~~~~~~~~~^~~~~~~~~
/usr/include/c++/14/bits/stl_vector.h:1283:7: note: candidate: 'void std::vector<_Tp, _Alloc>::push_back(const value_type&) [with _Tp = std::pair<std::__cxx11::basic_string<char>, int>; _Alloc = std::allocator<std::pair<std::__cxx11::basic_string<char>, int> >; value_type = std::pair<std::__cxx11::basic_string<char>, int>]'
 1283 |       push_back(const value_type& __x)
      |       ^~~~~~~~~
/usr/include/c++/14/bits/stl_vector.h:1283:7: note:   candidate expects 1 argument, 2 provided
/usr/include/c++/14/bits/stl_vector.h:1300:7: note: candidate: 'void std::vector<_Tp, _Alloc>::push_back(value_type&&) [with _Tp = std::pair<std::__cxx11::basic_string<char>, int>; _Alloc = std::allocator<std::pair<std::__cxx11::basic_string<char>, int> >; value_type = std::pair<std::__cxx11::basic_string<char>, int>]'
 1300 |       push_back(value_type&& __x)
      |       ^~~~~~~~~
/usr/include/c++/14/bits/stl_vector.h:1300:7: note:   candidate expects 1 argument, 2 provided
a.cc:15:16: error: no matching function for call to 'std::vector<std::pair<std::__cxx11::basic_string<char>, int> >::push_back(const char [4], int)'
   15 |   day.push_back("THU",3) ;
      |   ~~~~~~~~~~~~~^~~~~~~~~
/usr/include/c++/14/bits/stl_vector.h:1283:7: note: candidate: 'void std::vector<_Tp, _Alloc>::push_back(const value_type&) [with _Tp = std::pair<std::__cxx11::basic_string<char>, int>; _Alloc = std::allocator<std::pair<std::__cxx11::basic_string<char>, int> >; value_type = std::pair<std::__cxx11::basic_string<char>, int>]'
 1283 |       push_back(const value_type& __x)
      |       ^~~~~~~~~
/usr/include/c++/14/bits/stl_vector.h:1283:7: note:   candidate expects 1 argument, 2 provided
/usr/include/c++/14/bits/stl_vector.h:1300:7: note: candidate: 'void std::vector<_Tp, _Alloc>::push_back(value_type&&) [with _Tp = std::pair<std::__cxx11::basic_string<char>, int>; _Alloc = std::allocator<std::pair<std::__cxx11::basic_string<char>, int> >; value_type = std::pair<std::__cxx11::basic_string<char>, int>]'
 1300 |       push_back(value_type&& __x)
      |       ^~~~~~~~~
/usr/include/c++/14/bits/stl_vector.h:1300:7: note:   candidate expects 1 argument, 2 provided
a.cc:16:16: error: no matching function for call to 'std::vector<std::pair<std::__cxx11::basic_string<char>, int> >::push_back(const char [4], int)'
   16 |   day.push_back("FRI",2) ;
      |   ~~~~~~~~~~~~~^~~~~~~~~
/usr/include/c++/14/bits/stl_vector.h:1283:7: note: candidate: 'void std::vector<_Tp, _Alloc>::push_back(const value_type&) [with _Tp = std::pair<std::__cxx11::basic_string<char>, int>; _Alloc = std::allocator<std::pair<std::__cxx11::basic_string<char>, int> >; value_type = std::pair<std::__cxx11::basic_string<char>, int>]'
 1283 |       push_back(const value_type& __x)
      |       ^~~~~~~~~
/usr/include/c++/14/bits/stl_vector.h:1283:7: note:   candidate expects 1 argument, 2 provided
/usr/include/c++/14/bits/stl_vector.h:1300:7: note: candidate: 'void std::vector<_Tp, _Alloc>::push_back(value_type&&) [with _Tp = std::pair<std::__cxx11::basic_string<char>, int>; _Alloc = std::allocator<std::pair<std::__cxx11::basic_string<char>, int> >; value_type = std::pair<std::__cxx11::basic_string<char>, int>]'
 1300 |       push_back(value_type&& __x)
      |       ^~~~~~~~~
/usr/include/c++/14/bits/stl_vector.h:1300:7: note:   candidate expects 1 argument, 2 provided
a.cc:17:16: error: no matching function for call to 'std::vector<std::pair<std::__cxx11::basic_string<char>, int> >::push_back(const char [4], int)'
   17 |   day.push_back("SAT",1) ;
      |   ~~~~~~~~~~~~~^~~~~~~~~
/usr/include/c++/14/bits/stl_vector.h:1283:7: note: candidate: 'void std::vector<_Tp, _Alloc>::push_back(const value_type&) [with _Tp = std::pair<std::__cxx11::basic_string<char>, int>; _Alloc = std::allocator<std::pair<std::__cxx11::basic_string<char>, int> >; value_type = std::pair<std::__cxx11::basic_string<char>, int>]'
 1283 |       push_back(const value_type& __x)
      |       ^~~~~~~~~
/usr/include/c++/14/bits/stl_vector.h:1283:7: note:   candidate expects 1 argument, 2 provided
/usr/include/c++/14/bits/stl_vector.h:1300:7: note: candidate: 'void std::vector<_Tp, _Alloc>::push_back(value_type&&) [with _Tp = std::pair<std::__cxx11::basic_string<char>, int>; _Alloc = std::allocator<std::pair<std::__cxx11::basic_string<char>, int> >; value_type = std::pair<std::__cxx11::basic_string<char>, int>]'
 1300 |       push_back(value_type&& __x)
      |       ^~~~~~~~~
/usr/include/c++/14/bits/stl_vector.h:1300:7: note:   candidate expects 1 argument, 2 provided