local function main()
    a,b,x=io.read("*n","*n","n")
    c=2*x/a/b
    if c<=a then
        print(180*math.atan(b/c)/math.acos(-1))
    else
        print(180*math.atan((2*b-2*x/a/a)/a)/math.acos(-1))
    end
end

main()