Shuryga,
<!DOCTYPE html>
<html>
<head>
<title>Untitled</title>
<meta charset="utf-8">
<style type="text/css">
</style>
<script src="https://ajax.googleapis.com/ajax/libs/jquery/1.12.4/jquery.min.js"></script>
<script>
$(function() {
var one = $(".one"), old = "null";
one.on("mouseenter", ".click, .click-on", function(event) {
var index = one.index(event.delegateTarget);
$("p").html("from " + old + " to " + index);
old = index;
})
});
</script>
</head>
<body>
<p>index</p>
<div class='one'>
<div class='two'>
<div class='click'>
С него переходим
</div>
</div>
</div>
<div class='one'>
<div class='two'>
<div class='three'>
<div class='click-on'>
На него переходим
</div>
</div>
</div>
</div>
<div class='one'>
<div class='click-on'>
На него переходим
</div>
</div>
</body>
</html>