main.cpp: In function 'int main()':
main.cpp:6:5: error: 'cout' was not declared in this scope
    6 |     cout << "Hello World";
      |     ^~~~
main.cpp:2:1: note: 'std::cout' is defined in header '<iostream>'; this is probably fixable by adding '#include <iostream>'
    1 | #include <cstdio>
  +++ |+#include <iostream>
    2 | using namespace std;

A: Where's your header <iostream>?
B: Oh, I forgot to #include <iostream>.

main.cpp:4:1: error: 'cout' does not name a type
    4 | cout << "Hello World";
      | ^~~~

A: Where's the main function?
B: Oh, I forgot the main function.

main.cpp: In function 'int main()':
main.cpp:5:5: error: 'cout' was not declared in this scope; did you mean 'std::cout'?
    5 |     cout << "Hello World";
      |     ^~~~
      |     std::cout
In file included from main.cpp:1:
/usr/include/c++/15.1.0/iostream:65:18: note: 'std::cout' declared here
   65 |   extern ostream cout;          ///< Linked to standard output
      |                  ^~~~

A: Where's the namespace std?
B: Oh, I forgot using namespace std.

main.cpp: In function 'int main()':
main.cpp:6:26: error: expected ';' before 'return'
    6 |     cout << "Hello World"
      |                          ^
      |                          ;
    7 |     return 0;
      |     ~~~~~~                

...