PI = 3.14159265358979323846

a,b,x = gets.split.map(&:to_i)

s = 1.0 * x / a
ans = 0
a2  = 0

if s == a * b
  ans = 0
else
  if s > b * a / 2.0
    bu = 2.0 * s / a - b
    s -= a * bu
    b -= bu
    a2 = 2.0 * s / b
  else
    a2 = 2.0 * s / b
  end
  r = Math.atan((1.0*b)/a2)
  ans = r * (180.0/PI)
end

puts ans