CF152E Garden

Vasya has a very beautiful country garden that can be represented as an $ n×m $ rectangular field divided into $ n·m $ squares. One beautiful day Vasya remembered that he needs to pave roads between $ k $ important squares that contain buildings. To pave a road, he can cover some squares of his garden with concrete. For each garden square we know number $ a_{i}_{j} $ that represents the number of flowers that grow in the square with coordinates $ (i,j) $ . When a square is covered with concrete, all flowers that grow in the square die. Vasya wants to cover some squares with concrete so that the following conditions were fulfilled: - all $ k $ important squares should necessarily be covered with concrete - from each important square there should be a way to any other important square. The way should go be paved with concrete-covered squares considering that neighboring squares are squares that have a common side - the total number of dead plants should be minimum As Vasya has a rather large garden, he asks you to help him.

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