function isNumberKey(evt,sign)
{
  var charCode = (evt.which) ? evt.which : evt.keyCode;
  if(charCode==45){
	if(!sign) return false;
	var targ;
    if (evt.target) targ = evt.target;
    else if (evt.srcElement) targ = evt.srcElement;
    if (targ.nodeType == 3) // defeat Safari bug
	  targ = targ.parentNode;
    if(targ.value.indexOf('-')!==-1) return false;
    if(targ.selectionStart>1) return false;
  }
  if (charCode!=45 && charCode > 31 && (charCode < 48 || charCode > 57) &&
      charCode!=39 && charCode!=37 && charCode!=46)
     return false;
  return true;
}