a,b,x = gets.split.map(&:to_f)

if a ** 2 * b / 2 < x
    y = 2 * (a ** 2 * b - x) / (a ** 2)
    puts Math.atan(y/a) * 180 / Math::PI
else
    y = 2 * x / (a * b)
    puts 90 - Math.atan(y/b) * 180 / Math::PI
end