function set(n)
 {
  temp = document.main.elements.length  ;
  for (i=0; i < temp; i++)
  {
   document.main.elements[i].checked=n;
  }
 }
 function Invers()
 {
  temp = document.main.elements.length ;
  for (i=0; i < temp; i++)
  {
   if(document.main.elements[i].checked == 1){document.main.elements[i].checked = 0;}
   else {document.main.elements[i].checked = 1}
  }
 }