foo.cc: In function 'int main()':
foo.cc:8:9: error: 'cin' was not declared in this scope
    8 |         cin >> a;
      |         ^~~
foo.cc:1:1: note: 'std::cin' is defined in header '<iostream>'; did you forget to '#include <iostream>'?
  +++ |+#include <iostream>
    1 | using namespace std;
foo.cc:15:9: error: 'cout' was not declared in this scope
   15 |         cout << d << endl;
      |         ^~~~
foo.cc:15:9: note: 'std::cout' is defined in header '<iostream>'; did you forget to '#include <iostream>'?
foo.cc:15:22: error: 'endl' was not declared in this scope
   15 |         cout << d << endl;
      |                      ^~~~
foo.cc:1:1: note: 'std::endl' is defined in header '<ostream>'; did you forget to '#include <ostream>'?
  +++ |+#include <ostream>
    1 | using namespace std;
foo.cc:16:9: error: 'system' was not declared in this scope
   16 |         system("pause");
      |         ^~~~~~
foo.cc:6:13: warning: unused variable 'c' [-Wunused-variable]
    6 |         int c = 1;
      |             ^

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