/in/foo.c: In function 'main':
/in/foo.c:28:25: error: 'real' undeclared (first use in this function)
   28 |                         real=-b/(2*a);
      |                         ^~~~
/in/foo.c:28:25: note: each undeclared identifier is reported only once for each function it appears in
/in/foo.c:29:25: error: 'imag' undeclared (first use in this function)
   29 |                         imag=sqrt(-delta)/(2*a);
      |                         ^~~~
/in/foo.c:34:9: error: expected declaration or statement at end of input
   34 |         }
      |         ^