public static void DevideEven(BinTreeNode <int> S)
 {
     if (S != null)
     {
         if (S.GetValue() % 2 == 0)
         {
             S.SetValue(S.GetValue() / 2);
         }
         DevideEven(S.GetLeft());
         DevideEven(S.GetRight());
     }
 }