function changeMySrc(i) {

	switch(i)
	{
		case 1:
	   	  document.getElementById("plus1").src="./images/minus_dot.jpg";
    	  document.getElementById("plus2").src="./images/plus_dot.jpg";
    	  document.getElementById("plus3").src="./images/plus_dot.jpg";
		  break;
		case 2:
	   	  document.getElementById("plus1").src="./images/plus_dot.jpg";
    	  document.getElementById("plus2").src="./images/minus_dot.jpg";
    	  document.getElementById("plus3").src="./images/plus_dot.jpg";
		  break;
		case 3:
	   	  document.getElementById("plus1").src="./images/plus_dot.jpg";
    	  document.getElementById("plus2").src="./images/plus_dot.jpg";
    	  document.getElementById("plus3").src="./images/minus_dot.jpg";
		  break;
		default:
		break;
	}

}