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

if a ** 2 * b < 2 * x
    c = 2 * (b - (x).fdiv(a ** 2))
    puts 90 - Math.atan(a/c) * 180 / Math::PI
else
    c = (2 * x).fdiv(a * b)
    puts 90 - Math.atan(c/b) * 180 / Math::PI
end