Python 3.x, matrix doesn't work as intended

Question

sorry if the answer could be easy, but i really can't understand why this is giving me so much problems...

I want to populate a matrix with elements of another list, but when i do Matrix[0][1] = 1 it modifies the second colums of EVERY row, instead of just the first row. I had never happened this problem before, i don't really understand.

This is the code:

NumAlberi = int(input())
AltezAlb = ["a"] * NumAlberi
NumVele = ["b"] * NumAlberi
valori = [[0] * NumAlberi] * NumAlberi
for c in range(NumAlberi):
    AltezAlb[c], NumVele[c] = map(int, input().split())
ListaOrdinata = [[0] * 2] * NumAlberi
a = list(AltezAlb)
b = list(NumVele)
c = 0
print(ListaOrdinata)

while c < NumAlberi:
    if c % 2 == 0:
        tmp = max(a)
        ListaOrdinata[c][0] = tmp
        a.remove(tmp)
    else:
        tmp = min(a)
        ListaOrdinata[c][0] = tmp
        a.remove(tmp)
    ListaOrdinata[0][1] = 1
    c += 1
    print(ListaOrdinata, a)
print(ListaOrdinata)```

This is the output:

[[0, 0], [0, 0], [0, 0], [0, 0], [0, 0], [0, 0]]
[[5, 1], [5, 1], [5, 1], [5, 1], [5, 1], [5, 1]] [3, 4, 2, 4, 3]
[[2, 1], [2, 1], [2, 1], [2, 1], [2, 1], [2, 1]] [3, 4, 4, 3]
[[4, 1], [4, 1], [4, 1], [4, 1], [4, 1], [4, 1]] [3, 4, 3]
[[3, 1], [3, 1], [3, 1], [3, 1], [3, 1], [3, 1]] [4, 3]
[[4, 1], [4, 1], [4, 1], [4, 1], [4, 1], [4, 1]] [3]
[[3, 1], [3, 1], [3, 1], [3, 1], [3, 1], [3, 1]] []
[[3, 1], [3, 1], [3, 1], [3, 1], [3, 1], [3, 1]]

for example, at the end of everything, the last line of output should be:
[[5, 0], [2, 0], [4, 0], [3, 0], [4, 0], [3, 0]]
Thank you in advance

This is why: `valori = [[0] * NumAlberi] * NumAlberi`. Each row of this matrix is a reference to the same object. — Mad Physicist, Aug 06 '20 at 18:40
Or rather it's `ListaOrdinata = [[0] * 2] * NumAlberi`, but the idea is the same. — Mad Physicist, Aug 06 '20 at 18:40
English translation of variable names `NumAlberi` = number of masts, `AltezAlb` = height of masts, `NumVele` = number of sails, `ListaOrdinata` = ordered list `valori` = values — alani, Aug 06 '20 at 18:41
@alaniwi. Thanks. Any name is equally good as long as it's reasonably distinct and applied consistently. — Mad Physicist, Aug 06 '20 at 18:42

Python 3.x, matrix doesn't work as intended

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