include Math
a,b,x = gets.split.map(&:to_i)
s = a**2*b

if x == s/2.0
    ans = atan2(a,b)
elsif x < s/2.0
    c = x/(a*b.to_f)*2
    ans = atan2(c,b)
else
    c = x/(a**2.to_f)
    ans = atan2(a,(b-c)*2)
end

p 90 - ans/PI*180