program quad2
  implicit none

  real a,b,c,D,x1,x2,x1real,x1imag,x2real,x2imag

  write(*,'(a,$)') 'input coefficients a, b, c: '
  read(*,*) a,b,c

  D = b*b - 4.0*a*c

  if(D .gt. 0.0)then

     if ( b .ge. 0.0 ) then
        x2 = ( -b - sqrt( D ) ) / ( 2.0*a )
        x1 = c / a / x2
     else if ( b .lt. 0.0 ) then
        x1 = ( -b + sqrt( D ) ) / ( 2.0*a )
        x2 = c / a / x1
     end if
     write(*,'(2e16.8)') x1,x2

  else if(D .eq. 0.0)then
     
     write(*,'(e15.8)') -b / (2.0*a)

  else if(D .lt. 0.0)then

     x1real = -b / (2.0*a)
     x2real = x1real
     x1imag = sqrt( -D ) / (2.0*a)
     x2imag = -x1imag

     write(*,'(2e15.8,a)') x1real,x1imag,'i'
     write(*,'(2e15.8,a)') x2real,x2imag,'i'

  end if

end program quad2