program prob4
    implicit none
    integer::a,b,x
    real(8)::aa,bb,xx
    real(8),parameter::pi=3.141592653589793_8
    read(*,*) a,b,x
    aa = dble(a)
    bb = dble(b)
    xx = dble(x)
    if(2*x < a*a*b) then
        write(*,*) 90.0_8 - atan(2.0_8*xx / (aa*bb*bb))*180.0_8/pi
    else
        write(*,*) atan((2.0_8*bb - 2.0_8*xx/aa**2) / aa)*180.0_8/pi
    end if
    stop
end program