foo.cc: In function ‘int main()’:
foo.cc:6:9: error: ‘cin’ was not declared in this scope
    6 |         cin>>a>>b;
      |         ^~~
foo.cc:2:1: note: ‘std::cin’ is defined in header ‘<iostream>’; did you forget to ‘#include <iostream>’?
    1 | #include <stdio.h>
  +++ |+#include <iostream>
    2 | using namespace std;
foo.cc:7:9: error: ‘cout’ was not declared in this scope
    7 |         cout << a+b << endl;
      |         ^~~~
foo.cc:7:9: note: ‘std::cout’ is defined in header ‘<iostream>’; did you forget to ‘#include <iostream>’?
foo.cc:7:24: error: ‘endl’ was not declared in this scope
    7 |         cout << a+b << endl;
      |                        ^~~~
foo.cc:2:1: note: ‘std::endl’ is defined in header ‘<ostream>’; did you forget to ‘#include <ostream>’?
    1 | #include <stdio.h>
  +++ |+#include <ostream>
    2 | using namespace std;