a,b,x = gets.split.map(&:to_f)
t = x/a**2
at = a*t

if at < a*b/2
  d = 2 * at / b
  ans = Math.atan(b/d) * 180 / Math::PI
else
  d = 2*(b-x/(a**2))
  ans = Math.atan(d/a) * 180 / Math::PI
end

puts ans