[jQuery] Find index of div with class "selected"

[jimster]

I'm trying to get the index of a div marked as selected, it's all a
bit complicated because I have two levels of selected divs.

My mark up looks like this:

                <div id="container">
                        <div id="kid1" class="kid selected">
                                <div id="k1w1" class="week selected"></div>
                                <div id="k1w2" class="week"></div>
                                <div id="k1w3" class="week"></div>
                                <div id="k1w4" class="week"></div>
                        </div>

                        <div id="kid2" class="kid">
                                <div id="k2w1" class="week"></div>
                                <div id="k2w2" class="week"></div>
                                <div id="k2w3" class="week"></div>
                                <div id="k2w4" class="week"></div>
                        </div>

                        <div id="kid3" class="kid">
                                <div id="k3w1" class="week"></div>
                                <div id="k3w2" class="week"></div>
                                <div id="k3w3" class="week"></div>
                                <div id="k3w4" class="week"></div>
                        </div>

                        <div id="kid4" class="kid">
                                <div id="k4w1" class="week"></div>
                                <div id="k4w2" class="week"></div>
                                <div id="k4w3" class="week"></div>
                                <div id="k4w4" class="week"></div>
                        </div>
                </div>

What would be the correct code to grab the index of the third nested
div with the class "selected"?

I've tried things like:

var sk = "#container > div:eq(0)";
var swi = $(sk + " > div").index($(".selected"));

It's probably pretty obvious I'm stumbling in the dark...