function keyDown(event){
  var inputs = $(".txt");
  var focus = document.activeElement;
  if(!document.getElementById('mm').contains('focus')){
    return;
  };
  var event = window.event||event;
  var key = event.keyCode;
  var flag = -1;

  for(var i=0;i=0;j=j-2){
        if(inputs.get(j).disabled==false){
          flag = true;
          break;
        }
      }
    }
    if(flag){
      inputs[j].focus();
    }
    break;
  case 40:
      var j = i+2;
      var flag = false;
      if(inputs.get(j).disabled==false){
        flag = true;
      }else{
        for(j=i+4;j