desk = [[1, 2, 3], [4, 5, 6], [7, 8, 9]]

n = len(desk)
m = len(desk[0])
result = [[0] * n for i in range(m)]

for i in range(n):
    for j in range(m):
        result[j][n-i-1] = desk[i][j]

print(result)