local a, b, x = io.read("*n", "*n", "*n")
x = x / a
if a * b / 2 < x then
  local bd = (a * b - x) * 2 / a
  print(math.atan2(bd, a) / math.pi * 180)
else
  local ad = x * 2 / b
  print(math.atan2(b, ad) / math.pi * 180)
end
