/in/foo.cc: In function 'int main()':
/in/foo.cc:7:20: error: 'b' cannot be used as a function
    7 |         if(abs(a<=b(a,b))&&abs(a>=b(a,b)))
      |                   ~^~~~~
/in/foo.cc:7:36: error: 'b' cannot be used as a function
    7 |         if(abs(a<=b(a,b))&&abs(a>=b(a,b)))
      |                                   ~^~~~~