foo.cc: In function ‘int main()’:
foo.cc:5:9: error: ‘cin’ was not declared in this scope
    5 |         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:6:9: error: ‘cout’ was not declared in this scope
    6 |         cout<<a*a*a<<endl;
      |         ^~~~
foo.cc:6:9: note: ‘std::cout’ is defined in header ‘<iostream>’; did you forget to ‘#include <iostream>’?
foo.cc:6:22: error: ‘endl’ was not declared in this scope
    6 |         cout<<a*a*a<<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;