function changebtmtab(num){
var num;
var idn;
var cn;
var sh;
document.getElementById('n5').className='n5';
document.getElementById('n6').className='n6';
document.getElementById('n7').className='n7';
document.getElementById('n8').className='n8';
document.getElementById('s5').style.display='none';
document.getElementById('s6').style.display='none';
document.getElementById('s7').style.display='none';
document.getElementById('s8').style.display='none';

idn='n' + num;
sh='s' + num;
cn=idn + num;
document.getElementById(idn).className=cn;
document.getElementById(sh).style.display='block';
}