include Math
def rad_to_deg(rad)
    rad * 360  / (2 * PI)
end

a, b, x  = gets.split.map(&:to_f)
if a * a * b / 2 >= x
    p 90 -  rad_to_deg(atan(2 * x / (a * b * b)))
else
    p rad_to_deg(atan(2 * (b / a - x / a ** 3)))
end
