/in/foo.c: In function 'main':
/in/foo.c:21:44: warning: 'i' may be used uninitialized [-Wmaybe-uninitialized]
   21 |                         x1=(-b-sqrt(-delta)*i)/(2*a);
      |                                ~~~~~~~~~~~~^~
/in/foo.c:20:29: note: 'i' was declared here
   20 |                         int i;
      |                             ^