运行 ID: 822

Main.cc: In function ‘int main()’:
Main.cc:11:9: error: ‘cin’ was not declared in this scope
         cin>>a;
         ^~~
Main.cc:11:9: note: suggested alternative:
In file included from Main.cc:1:0:
/usr/include/c++/7/iostream:60:18: note:   ‘std::cin’
   extern istream cin;  /// Linked to standard input
                  ^~~
Main.cc:12:9: error: ‘cout’ was not declared in this scope
         cout<