Change your function to:

```
def filtra_ordinati(l1):
l2 = []
for y in range(1,len(l1)):
if l1[y-1] < l1[y]:
print(f'I will add {l1[y-1]} because it smaller then {l1[y]}')
l2.append(l1[y-1])
return l2
L1 = [1, 2, 5, 4, 7, 8, 3, 9]
print(f'list is {L1}')
print(filtra_ordinati(L1))
```

And you will see what you adding inside list and why.

Output will be:

```
list is [1, 2, 5, 4, 7, 8, 3, 9]
I will add 1 because it smaller then 2
I will add 2 because it smaller then 5
I will add 4 because it smaller then 7
I will add 7 because it smaller then 8
I will add 3 because it smaller then 9
[1, 2, 4, 7, 3]
```

The correct function is:

```
def f(l):
l2 = l[:1]
for el in l:
if el > l2[-1]:
l2.append(el)
return l2
```

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