program main
 implicit none
 real*8 a,b,x,theta,pi
 pi = 4.D0*atan(1.D0)
 read(*,*) a,b,x
 if(x > (a*a*b)/2) then
  theta = atan2(2*(a*a*b-x)/(a*a),a)
 else
  theta = atan2(b,2*x/(a*b))
 end if
 write(*,*) theta*180/pi
end program main