#set
include Math
a,b,x = gets.chomp.split(" ").map(&:to_i)
s = x / a
limit = (a * b) / 2
# limit = ( 2 *((a ** 2) * b - x ) ) / (a ** 3) 

#main
# answer = Math.atan(limit)
# p limit
# p answer * (180 / Math::PI)

if s <= limit then
  h = (2 * s) / b
  rad = Math.atan2(h ,b) 
else
  h = 2 * (a * b - s) / a
  rad = Math.atan2(a, h)
end
answer = rad * 180 / PI

print ("#{answer}\n")