a,b,x = gets.split.map &:to_i

d = x * 1.0 / (a * a)

if d * a * 2.0 / b >= a then
	b2 = d * a * 2 / a - b
	puts Math.atan((b - b2) / a) / ( 2 * Math::PI) * 360
else
	a2 = d * a * 2 / b
	puts Math.atan(b / a2) / ( 2 * Math::PI) * 360
end
