parser.add_argument("--stack_nb_stacks", type=int, default=1)
 
-parser.add_argument("--stack_nb_digits", type=int, default=1)
+parser.add_argument("--stack_nb_digits", type=int, default=3)
+
+parser.add_argument("--stack_fraction_values_for_train", type=float, default=None)
 
 ######################################################################
 
         nb_steps,
         nb_stacks,
         nb_digits,
+        fraction_values_for_train=None,
         device=torch.device("cpu"),
     ):
         self.batch_size = batch_size
         self.nb_digits = nb_digits
         self.device = device
 
+        if fraction_values_for_train is None:
+            values_for_train = None
+            values_for_test = None
+        else:
+            all = torch.randperm(10**nb_digits)
+            nb_for_train = int(all.size(0) * fraction_values_for_train)
+            values_for_train = all[:nb_for_train]
+            values_for_test = all[nb_for_train:]
+
         self.train_input, self.train_stack_counts = stack.generate_sequences(
-            nb_train_samples, nb_steps, nb_stacks, nb_digits, self.device
+            nb_train_samples,
+            nb_steps,
+            nb_stacks,
+            nb_digits,
+            values_for_train,
+            self.device,
         )
 
         self.test_input, self.test_stack_counts = stack.generate_sequences(
-            nb_test_samples, nb_steps, nb_stacks, nb_digits, self.device
+            nb_test_samples,
+            nb_steps,
+            nb_stacks,
+            nb_digits,
+            values_for_test,
+            self.device,
         )
 
         mask = self.test_input.clone()
             )
 
             #!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
-            input = self.test_input[:10, :20]
+            input = self.test_input[:10, :50]
             result = input.clone()
             stack.remove_popped_values(result, self.nb_stacks, self.nb_digits)
             ar_mask = (result != input).long()
         nb_steps=args.stack_nb_steps,
         nb_stacks=args.stack_nb_stacks,
         nb_digits=args.stack_nb_digits,
+        fraction_values_for_train=args.stack_fraction_values_for_train,
         device=device,
     )
 
 
 # CODE_VAL=val + 2 * nb_stacks
 
 
-def generate_sequences(nb, nb_steps, nb_stacks, nb_digits, device=torch.device("cpu")):
+def generate_sequences(
+    nb, nb_steps, nb_stacks, nb_digits, values=None, device=torch.device("cpu")
+):
     stack = torch.empty(nb, nb_stacks, nb_steps, dtype=torch.int64)
     stack_counts = torch.zeros(nb, nb_stacks, dtype=torch.int64)
     k = torch.arange(nb)
         op = torch.randint(2, (nb,))
         st = torch.randint(nb_stacks, (nb,))
         op = op * (stack_counts[k, st] > 0)
-        val_push = torch.randint(10**nb_digits, (nb,))
+        if values is None:
+            val_push = torch.randint(10**nb_digits, (nb,))
+        else:
+            val_push = values[torch.randint(values.size(0), (nb,))]
         val_pop = stack[
             k,
             st,