编写一个程序，输出九九乘法表。一共有九行，每一行之间都要换行，每一个算式之间以空格划分。

样例输入

1 x 1 = 1
1 x 2 = 2   2 x 2 = 4
............
1 x 9 = 9   2 x 9 = 18   3 x 9 = 27   4 x 9 = 36   5 x 9 = 45   6 x 9 = 54   7 x 9 = 63   8 x 9 = 72   9 x 9 = 81