a, b, x = gets.chomp.split(" ").map(&:to_i)
hen = (2 * x - b * (a ** 2)) / a ** 2
hen = b - hen
if hen >= 0
    ans = a / hen.to_f
    kakudo = Math.atan(ans) * 180 / Math::PI
elsif hen < 0
    mizikai = a * (b / (hen.abs + b))
    ans = mizikai / b .to_f
    kakudo = Math.atan(ans) * 180 / Math::PI

end
puts kakudo