function toggle_visibility(id) {
    
    
       var e = document.getElementById(id);
       if(e.style.display == 'block')
          e.style.display = 'none';
       else
          e.style.display = 'block';
          
          
        var eDva = document.getElementById('sub2');
       if(eDva.style.display == 'block')
          eDva.style.display = 'none';
       else
          eDva.style.display = 'block';
          
          
       var eTRI = document.getElementById('sub3');
       if(eTRI.style.display == 'block')
          eTRI.style.display = 'none';
       else
          eTRI.style.display = 'block';
          
          
         var eCETIRI = document.getElementById('sub4');
       if(eCETIRI.style.display == 'block')
          eCETIRI.style.display = 'none';
       else
          eCETIRI.style.display = 'block';
          
          
                
         var ePET = document.getElementById('sub5');
       if(ePET.style.display == 'block')
          ePET.style.display = 'none';
       else
          ePET.style.display = 'block';


         var eSEST = document.getElementById('sub6');
       if(eSEST.style.display == 'block')
          eSEST.style.display = 'none';
       else
          eSEST.style.display = 'block';


         var eSEDAM = document.getElementById('sub7');
       if(eSEDAM.style.display == 'block')
          eSEDAM.style.display = 'none';
       else
          eSEDAM.style.display = 'block';          
          
          
          
          
    }