function sel(id){
		  if(id==1){
		    document.getElementById('sel_1').className="bk01";
		    document.getElementById('sel_2').className="bk02";
		    document.getElementById('sel_3').className="bk02";
			document.getElementById('sel_4').className="bk02";
			document.getElementById('sel_1c').style.display="block";
			document.getElementById('sel_2c').style.display="none";
			document.getElementById('sel_3c').style.display="none";
			document.getElementById('sel_4c').style.display="none";
			}
		  else if(id==2){
		    document.getElementById('sel_1').className="bk02";
		    document.getElementById('sel_2').className="bk01";
		    document.getElementById('sel_3').className="bk02";
			document.getElementById('sel_4').className="bk02";
			document.getElementById('sel_1c').style.display="none";
			document.getElementById('sel_2c').style.display="block";
			document.getElementById('sel_3c').style.display="none";
			document.getElementById('sel_4c').style.display="none";
		  }
		  else if(id==3){
		    document.getElementById('sel_1').className="bk02";
		    document.getElementById('sel_2').className="bk02";
		    document.getElementById('sel_3').className="bk01";
			document.getElementById('sel_4').className="bk02";
			document.getElementById('sel_1c').style.display="none";
			document.getElementById('sel_2c').style.display="none";
			document.getElementById('sel_3c').style.display="block";
			document.getElementById('sel_4c').style.display="none";
		  }
		  else if(id==4){
		    document.getElementById('sel_1').className="bk02";
		    document.getElementById('sel_2').className="bk02";
		    document.getElementById('sel_3').className="bk02";
			document.getElementById('sel_4').className="bk01";
			document.getElementById('sel_1c').style.display="none";
			document.getElementById('sel_2c').style.display="none";
			document.getElementById('sel_3c').style.display="none";
			document.getElementById('sel_4c').style.display="block";
		  }  
		  }