/in/foo.cc: In function 'int main()':
/in/foo.cc:13:12: error: 'sum' cannot be used as a function
   13 |         sum(0);
      |         ~~~^~~
/in/foo.cc:14:21: error: 'maxx' cannot be used as a function
   14 |                 maxx(0);
      |                 ~~~~^~~