def bloc(S,i,j):
    r = []
    ligne = (i // 3) * 3
    colonne = (j // 3) * 3
    for l in  [ligne,ligne+1,ligne+2]:
        for c in [colonne,colonne+1,colonne+2]:
            if S[l][c] != 0:
                r.append(S[l][c])
    return r