include Math
a,b,x = gets.split.map(&:to_f)
S = x / a

if S <= a * b / 2.0
  a_ = 2.0 * S / b
  puts atan2(b, a_) * 180.0 / PI
else
  S_ = a * b - S
  b_ = 2.0 * S_ / a
  puts atan2(b_, a) * 180.0 / PI
end
