[melky]

<style>
* {margin:0;padding:0}
.green {background-color:#77FC79}
.red {background-color:#FA4B57}
div.block {
    margin: 30px;
    border:1px #2E2E2E solid;
    text-align:center;
    padding:10px 0px;
    width:100px;
}
.left {
    position:absolute;
    left: 150px;
}
</style>

<div class="left">
    Clicked : <b id="res">0</b>
</div>


<div class="block red">hello</div>
<div class="block red">hello</div>
<div class="block red">hello</div>

<script>
window.onload = function(){
	var a = document.getElementById("res");
    document.body.onclick = function(e){
        var el = e ? e.target:event.srcElement;
		var cls = el.className;
		if(!~cls.indexOf("block")) return;
        if(~cls.indexOf("green")) {
        	el.className = "block red";
        	a.innerHTML--;
        } else {
        	el.className = "block green";
        	a.innerHTML++;
        }		
    }
}
</script>