n = int(input("Entrer la dimension de la matrice : "))
# matrice nulle
matrice_nulle = 
[ [ 0 for j in range(n)] for i in range(n)]

# matrice identité
matrice_id = [ [ 0 for j in range(n)] for i in range(n)]

for ligne in range(n):
    for c in range(n):
        if c == ligne:
            matrice_id[ligne][c] = 1
        else:
            matrice_id[ligne][c] = 0