function vk(kac){
 for(i=1;i<4;i++){
  if(i == kac){
   eval("document.getElementById('vkat_"+kac+"').style.display='block'");
   eval("document.getElementById('vkb_"+kac+"').className='vkbut2'");
  }else{
   eval("document.getElementById('vkat_"+i+"').style.display='none'");
   eval("document.getElementById('vkb_"+i+"').className='vkbut'");
  }
 }
}