function zhangquan(flag)
{
	switch(flag) {


	    case 0:


	        document.getElementById("x0").className = "y1";
	        document.getElementById("x1").className = "y2";
	        document.getElementById("x2").className = "y2";
	        break;

	    case 1:

		document.getElementById("x0").className = "y2";
		document .getElementById("x1").className ="y1";
		document .getElementById("x2").className="y2";
	

		
		break;
		case 2:


		document.getElementById("x0").className = "y2";
		document .getElementById("x1").className ="y2";
		document .getElementById("x2").className="y1";
	

		
		break;
		
		
	}
}
function NULL()
{
	return;
}