function getanImage()
{
    var ranNum= Math.floor(Math.random()*4);

    var right = new Array(4)
     right[0]= "images/rs1.jpg";
     right[1]= "images/rs2.jpg";
     right[2]= "images/rs3.jpg"; 
     right[3]= "images/rs4.jpg";
  
  
	document.right_img.src = right[ranNum]; 
	    
   }