line = gets.split(' ').map(&:to_f)

a = line[0]
b = line[1]
x = line[2]
PI = Math.atan(1) * 4

if x > (a ** 2) * b / 2 then
  tan = 2 * ((a ** 2) * b - x) / (a ** 3)
  print (Math.atan(tan) * 180 / PI)
else
  tan = a * (b ** 2) / (2 * x)
  print (Math.atan(tan) * 180 / PI)
end