Given two sparse matrices A and B, return the result of AB.

You may assume that A’s column number is equal to B’s row number.

**Example:**

Input:A= [

[ 1, 0, 0],

[-1, 0, 3]

]B= [

[ 7, 0, 0 ],

[ 0, 0, 0 ],

[ 0, 0, 1 ]

]Output:| 1 0 0 | | 7 0 0 | | 7 0 0 |AB= | -1 0 3 | x | 0 0 0 | = | -7 0 3 |

| 0 0 1 |