foo.cc: In function 'int main()':
foo.cc:9:2: error: 'cout' was not declared in this scope
    9 |  cout<<x<<endl;
      |  ^~~~
foo.cc:1:1: note: 'std::cout' is defined in header '<iostream>'; did you forget to '#include <iostream>'?
  +++ |+#include <iostream>
    1 | 
foo.cc:9:11: error: 'endl' was not declared in this scope
    9 |  cout<<x<<endl;
      |           ^~~~
foo.cc:1:1: note: 'std::endl' is defined in header '<ostream>'; did you forget to '#include <ostream>'?
  +++ |+#include <ostream>
    1 | 

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