function hideall()
{
	document.getElementById('layer1').style.visibility = 'hidden';
     document.getElementById('layer2').style.visibility = 'hidden'; 
	 document.getElementById('layer3').style.visibility = 'hidden'; 
	 document.getElementById('layer4').style.visibility = 'hidden';
	 document.getElementById('layer5').style.visibility = 'hidden';
	 document.getElementById('layer6').style.visibility = 'hidden';
}
function chklayer(v) {
     
     if (v == "0") {
     hideall();
	 document.getElementById('layer1').style.visibility = 'visible';
     
          return false;
     } else if (v == "1") {

     hideall();
	 document.getElementById('layer2').style.visibility = 'visible';
      
     } else if (v == "2") {
     hideall();
	 document.getElementById('layer3').style.visibility = 'visible';
     
      
     } else if (v == "3") {
     hideall();
	 document.getElementById('layer4').style.visibility = 'visible';
     
     }
	     else if (v == "4") {
	 hideall();
	 document.getElementById('layer5').style.visibility = 'visible';		  
     
     }
	 	     else if (v == "5") {
	 hideall();
	 document.getElementById('layer6').style.visibility = 'visible';
	
     }
	  	   
	 
     
}