A, B, X = gets.split.map(&:to_f)
TOTAL = A*A*B
T = 10**20

if X == TOTAL/2
  p 45
elsif X < TOTAL/2
  # 水が少ない
  ang = (0..45*T).bsearch {|angle|
    angle /= T.to_f
    rad = angle * Math::PI / 180
    h = Math.tan(rad) * B
    tri = B * h / 2
    mass = tri * A
    #p angle: angle
    mass - X < T
  } / T.to_f
  p 90 - ang
else
  # 水が多い
  ang = (0..45*T).bsearch {|angle|
    angle /= T.to_f
    rad = angle * Math::PI / 180
    h = Math.tan(rad) * A
    tri = A * h / 2
    mass = tri * A
    #p angle: angle, L: TOTAL-mass, R: X
    # trueを返すのは
    # 求める角度が     以下のとき
    # = angleが大きすぎるとき
    # = massが大きすぎるとき
    TOTAL - mass < X
  } / T.to_f
  p ang
end