Goods from three warehouses have to be delivered to five shops, the cost of transporting one unit of good from warehouse $i$ to shop $j$ being $c_{i j}$, where

$$C=\left(\begin{array}{ccccc} 2 & 3 & 6 & 6 & 4 \\ 7 & 6 & 1 & 1 & 5 \\ 3 & 6 & 6 & 2 & 1 \end{array}\right)$$

The requirements of the five shops are respectively $9,6,12,5$ and 10 units of the good, and each warehouse holds a stock of 15 units. Find a minimal-cost allocation of goods from warehouses to shops and its associated cost.