f=lambda m:m and m.pop(0)+f([list(x)for x in zip(*m)][::-1]) print(f([])) print(f([[1]])) print(f([[1,2],[4,3]])) print(f([[1,2,3],[8,9,4],[7,6,5]])) print(f([[1,2,3,4],[12,13,14,5],[11,16,15,6],[10,9,8,7]])) print(f([[1,2,3,4],[10,11,12,5],[9,8,7,6]]))