View Compilation Error

0_0_16221456_17058.c: In function 'main':
0_0_16221456_17058.c:11:6: error: '_int64' undeclared (first use in this function)
  if((_int64)(sqrt(b*b-4*a*c)*sqrt(b*b-4*a*c))==b*b-4*a*c && -b+sqrt(b*b-4*a*c)<0 && -b-sqrt(b*b-4*a*c)<0)
      ^
0_0_16221456_17058.c:11:6: note: each undeclared identifier is reported only once for each function it appears in