! 2019.10.27
!
      program answer
      implicit none
      integer :: a,b,x
      double precision :: a_d,b_d,x_d
      double precision :: theta
      double precision :: pi
      intrinsic datan,dble,abs
!
      pi = 3.14159265358979323846264338327950
      read(*,*) a,b,x
      a_d = dble(a)
      b_d = dble(b)
      x_d = dble(x)
      if(a_d*b_d/2.0 < x_d) then
        theta = datan(2.0d0*(a_d*b_d)/a_d**2.0d0-2.0d0*(x_d/a_d)/a_d**2.0d0)/pi*180.0d0
        if(abs(theta - 45.0d0) < 0.00001) then
          theta = 45.0d0
        end if
      else
        theta = datan((a_d*b_d**2.0d0)/(2.0d0*x_d))/pi*180.0d0
      end if
      write(*,*) theta
      end program answer