foo.cc: In function ‘int main()’:
foo.cc:6:12: error: ‘cout＜＜a’ was not declared in this scope
    6 |            cout＜＜a+b＜＜endl;
      |            ^~~~~~~~~
foo.cc:6:22: error: ‘b＜＜endl’ was not declared in this scope
    6 |            cout＜＜a+b＜＜endl;
      |                      ^~~~~~~~~
foo.cc:5:8: warning: unused variable ‘a’ [-Wunused-variable]
    5 |    int a,b;
      |        ^
foo.cc:5:10: warning: unused variable ‘b’ [-Wunused-variable]
    5 |    int a,b;
      |          ^
foo.cc: At global scope:
foo.cc:8:1: error: expected unqualified-id before ‘return’
    8 | return 0
      | ^~~~~~