运行 ID: 5025

Main.cc: In function ‘int main()’:
Main.cc:3:3: error: ‘n’ was not declared in this scope
   n;
   ^
Main.cc:4:2: error: ‘cin’ was not declared in this scope
  cin>>n;
  ^~~
Main.cc:4:2: 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:5:2: error: ‘cout’ was not declared in this scope
  cout<