运行 ID: 50831

Main.cc: In function ‘int main()’:
Main.cc:7:8: error: no match for ‘operator<<’ (operand types are ‘std::istream {aka std::basic_istream}’ and ‘int’)
     cin<
Main.cc:7:8: note:   no known conversion for argument 1 from ‘std::istream {aka std::basic_istream}’ to ‘int’
In file included from /usr/include/c++/7/regex:62:0,
                 from /usr/include/x86_64-linux-gnu/c++/7/bits/stdc++.h:110,
                 from Main.cc:1:
/usr/include/c++/7/bits/regex.h:1525:5: note: candidate: template std::basic_ostream<_CharT, _Traits>& std::__cxx11::operator<<(std::basic_ostream<_CharT, _Traits>&, const std::__cxx11::sub_match<_Bi_iter>&)
     operator<<(basic_ostream<_Ch_type, _Ch_traits>& __os,
     ^~~~~~~~
/usr/include/c++/7/bits/regex.h:1525:5: note:   template argument deduction/substitution failed:
Main.cc:7:10: note:   ‘std::istream {aka std::basic_istream}’ is not derived from ‘std::basic_ostream<_CharT, _Traits>’
     cin<