/in/foo.c: In function 'main':
/in/foo.c:11:9: error: 'd' undeclared (first use in this function)
   11 |         d=b*b-4*c*a;
      |         ^
/in/foo.c:11:9: note: each undeclared identifier is reported only once for each function it appears in
/in/foo.c:13:20: error: '\U0000ff08' undeclared (first use in this function)
   13 |                 x2=（-b-sqrt(m)）/2*a;
      |                    ^~
/in/foo.c:13:32: error: expected ';' before '\U0000ff09'
   13 |                 x2=（-b-sqrt(m)）/2*a;
      |                                ^~
      |                                ;